Anytime I have to use one of those it’s always a nightmare because they’re just so cramped, and I never really see the benefit of extra freezer space because unless I’m buying a million TV dinners or ice cream tubs I don’t really see the point.
They are easier to fit with an ice maker on the outside of the door?
Then you’re not the use case for them. We have a side-by-side and it works well for us. Both sides are pretty well stocked and it’s nice to have common items at eye/hand level on both sides. We didn’t do an ice maker or water dispenser though – always felt they were a waste of space in the unit and known too many people who had ruined kitchen floors when the unit failed and leaked.
Before I bought my house, I always lived in apartments that had refrigerators with the freezer “compartment”. Then my house came with a huge double door fridge/freezer and I thought I’d never need such a thing. But it didn’t take long to get used to it and now I can’t imagine how I managed without one. I usually keep the freezer side full, especially these days. Plus I love that it makes ice. I always hated having to use ice trays.
Like the previous poster, this house had our first side by side, and I think it’s great. I’d much rather shelves to look through than a drawer, where everything I want is always on the bottom.
I’m very much an,’out of sight, out of mind’, person, if I can’t see it, when I look in, I’m gonna forget it exists pretty easily.
Mine easily hold tons of stuff, (hubs loves to keep his larder stocked), and I have no issue finding things. I have a small chest freezer in the basement for oversized things like giant turkeys, etc. I love having everything else right there where I want it.
I also won’t do ice or water on the door, that’s not for me.
The benefit is space. If you’ve got enough room, then you can get a fridge and freezer of the size you want and put them in but if you haven’t, combinations work.
My kitchen is tiny (actually tiny, even for the UK - it’s about 8ft square) and for a long time we had a top/bottom split fridge freezer as our only cold storage, and we struggled a lot for freezer space. Now we’ve got separates, with a large enough freezer, but that freezer is necessarily in a different room on a different floor.
“Why do they make things that don’t suit me? What could possibly their motivation if my life wasn’t specifically catered to? It’s craaaaazy!”
I could fit everything I eat for a month into a single mini-fridge with a tiny freezer-box. Different use-cases for different people.
I am baffled as to what sort of fridge or freezer the OP is expecting to have instead. Perhaps (s)he’s not from the US and I’m just ignorant of local practice wherever.
I think the OP is talking about a side-by-side as opposed to a top or bottom freezer - in a top or bottom freezer model, the freezer compartment is usually smaller than the fridge compartment.
Are there really models that are half freezer?
I don’t know that my side-by-side really has much difference in volume than if it were above the fridge part.
Living in Arizona, ice and water on the door is a must. I’ve worn out three ice makers so far.
As other’s have mentioned, I don’t see the advantage of having to dig through a chest to find something. There’s only two of us, so we rarely run out of freezer space (and we have an overflow fridge/.freezer downstairs). So, side-by-side all the way!
If you take out the shelves, you can almost fit a whole body in a side-by-side. Stuffing one into a drawer or upper-freezer requires some butchery or origami skills.
Ah that explains their popularity.
Get rid of these type of posts and 1/3rd of the Dope would disappear. 
But, yeah, I had the exact same thought. Because I’m cheap and my refrigerator still (barely) works*, we have a really old model with the freezer on top, but we also have a freezer in the basement because one can never have too much freezer space. Actually, that’s not true, as freezers are more efficient the fuller they are (the opposite of refrigerators) so if one can’t pack a stand-alone freezer then one is better off managing the refrigerator’s freezer better.
*Our handle is about to break, so I googled looking for replacements, and a replacement for the plastic handle costs about 1/4 the amount of a new fridge. 
20 something years ago, when I had a side by side , it was pretty close to half and half. Maybe the fridge side was an inch or two wider , but not enough to make much difference. I think the newer ones split the volume similarly to a top or bottom freezer model.
To each his own. When I owned a house, I always had a side-by-side, with the freezer part narrower than the refrigerator part. To me, that’s the ideal setup.
Now that I rent and don’t have a choice, my unit has a fridge with a bottom freezer. I don’t care for it at all. As an aging dude with knee and back issues, I don’t like having to bend down whenever I need ice for my drink.
My order of preference: side-by-side, bottom drawer, top freezer, chest. And I would really rather not have either of the latter two.
Our problem with a side-by-side fridge/freezer was that a greater proportion of fridge items were “out of sight” (since it’s narrower than a normal fridge), and fridge items are worse to forget than freezer items.
Is the OP asking
- why people prefer the side-by-side layout, or
- why people want lots of freezer space?
If it’s #1, you may want to look at this recent thread:
I think it was originally a poll (unless I’m remembering a different thread), but the poll part doesn’t seem to have survived the transfer to Discourse.
If it’s #2:
Some people like to be able to stock up on things that are already frozen (not just TV dinners and ice cream, but other stuff comes frozen too),
Some people like to be able to stock up on things that aren’t frozen to begin with but will keep a lot longer if you put them in the freezer, and
Some people like to make large quantities of food and freeze the leftovers.
Yeah, I don’t like side-by-side, because the fridge is too narrow for a pizza box, and the freezer too narrow for a turkey. But I would like more freezer space. And I get that other people don’t put large things in the fridge.