During their heyday (late 70s-early 80s) I would have simply called them “mainstream rock”; but yeah, “Arena Rock” works for me. (I’m not sure ELO fits in with most of the rest of these bands, which are basic guitar-with-keyboards rock.) They were slickly-produced (no rough edges), radio-friendly, and had a high level of craftsmanship (as opposed to artistry)—and there’s nothing wrong with any of this, though their detractors often disparage them for it. Their songs run the gamut from the more melodic end of Hard Rock to at least the less wimpy part of Soft Rock—and without the danceability of Pop, the energy and attitude of Punk, or the soul of R&B. I listened to this stuff when I was in high school, and liked a fair amount of it, and I’m not ashamed to say I still listen to Styx, REO, Journey, et al occasionally. But yes, the worst of this stuff is cheezy and overplayed.
And Dennis DeYoung (of Styx) is the love child of Art Rock and Barry Manilow. Not that there’s anything wrong with that.