Hey Stalker0!
Well I probably used to think exactly the same. But the problem with 30 ish traits/attacks/legendary actions/lair actions is that:
1. Its off putting to some DMs to read such a stat-block
2. Even if they do read it, they probably won't remember most of it (either as set-up or in play)
3. The more powers you add the less focus the monster has
4. Likewise, more powers (especially more standardized powers) increases the likelihood that more of your high CR monsters share the same powers - making everything less unique - this is doubly true for Dragons
5. With this many powers you'll probably need multiple pages to explain it all. Meaning its not a stat-block at a glance any more - especially if there is page flipping.
6. Epic Play is already numerically the most complicated so anything you can do to alleviate the complexity rather than compound it will probably help.
Of course, all that said, epic gamers and DMs are probably more used to and more tolerable of higher complexity, but even then there is always the goal to not put off new epic level players and DMs.