Yeah, that last part is pretty ridiculous IMO.
My opinion is that seasons 4 and 5 were probably the high points of the series. The first few seasons you can tell were them trying to, as you mention, find their footing- the dialogue felt a bit more juvenile (though that's also probably because the episodes were more slice-of-life and episodic), and the lessons were pretty basic ones you'd find in your typical kids' show (e.g. don't judge a book by its cover, share your feelings with your friends, appreciate each other's differences). The later seasons seemed to keep up most of the same tone of seasons 4-5 and add a bit more depth to their lessons, and for the most part have maintained the quality of the show, but I do feel like the mane six are kind of running their course and it would be better to shift the spotlight to other characters, as it seems they've been doing with Starlight, Trixie, the school students and the Pillars. Either that or it's the new show writers (I'd really hate to point fingers here, but it's definitely a possibility).
This is also probably just me, but the later seasons also seem to be a bit more ham-fisted with their message and their execution, with episodes like School Daze, Fluttershy Leans In, and Fame and Misfortune.
Kind of an aside, but I personally actually think the map episodes are some of the best of the series. Aside from getting really cool new characters (the Las Pegasus Ponies, Saffron and Coriander, the Kirin, and Vapor and Sky), the Mane Six fill in the role of teachers. Sure, the way they're summoned (the all-knowing Cutie Map just "calls them") is pretty contrived and often feels forced, but usually the mane characters end up as something like guidance counselors, where, even though they mess up, they use their strengths to help push others in the right direction towards solving their problems. I like that about these episodes.
Discord's kinda an oddball. I feel like there's a lot he could do to mess with the ponies, but just doesn't, because he's just that capricious. It was pretty interesting to see that play out in A Matter of Principals, which actually makes me think he might be more powerful than the Tree of Harmony if he's able to tamper with the Cutie Map.
The school itself...is hard to describe. My opinion is that, in theory, it's a great idea and a natural progression of Twilight's role as Princess of Friendship, but in practice you just end up with something that should be way harder to deal with than the show makes it out to be. I was actually about to applaud the Season 8 premiere for introducing a sort of "checks-and-balances" where Twilight would have to deal with the intricacies of starting a school while also keeping with government laws, but in the end Neighsay's a racist and apparently the EEA are bad at actually making schools effective places to learn so their objections are pretty much invalidated (and it's treated as a good thing). But at least everything works out in the finale so...yay?