I got here late so, I’m probably repeating others but I still want my 2c 
Yep, absolutely. No-one should feel bad about liking or not liking anything.
Rap and hip hop though are somewhat unique in the degree of snobbishness and contempt levelled at them. I’ve seen it a bit on the dope, but much more elsewhere. That it’s not real music, that the world would be better without it etc.
I’m glad that the OP is very much not in that style, and is just honest inquisitiveness.
It’s something like a dialect; they use a lot of slang and being able to flow with the rhythm is more important than being very clear to the listener.
Most people who frequently listen to hip hop can indeed understand what is being said, though they may not be able to rap along with it, because rapping takes a degree of skill.
Generally-speaking this is not where the skill lies in rap music. It is more in writing lyrics that both make sense and flow, being able to perform that verse, and the music production side of creating catchy rhythms and fresh sounds etc.
I think hip hop doesn’t suit live performance as well as some other genres. Crucially, people often expect a high energy performance, with dancing, which is almost impossible to do while rapping and it’s hard to get the volume mix right live too.
I mean, I’ve been to some great shows, but you typically either have live rapping, or a very visual performance, but often not both at the same time, and for the superbowl they went with the latter.
It depends. It’s become a bit of a meme that rap doesn’t have a message, but actually there are a higher proportion of rap songs covering social issues than other genres IMO.
However, it’s also true that a lot of rap is about bragging, or just “keeping it real” i.e. admitting to a desire for money, sex, whatever, instead of pretending to be above all that. And it’s a performance thing…it’s equally likely to be self-parody these days.