There are some great points raised above.
For me the hey day of the tower was when the presence of Ayin Mesmer drew in some other great RP'ers. Not only did many arrive with their own RP plots and magical techniques, but as players learned a lot from and were inspired by him, which makes it fun. Sadly, we aren't allowed to clone Kuma.
As identified above by Diegovog, lectures are felt to be a spent as a force for RP, as the discussed concepts became overdone. This was particularly so as spell schools were repeatedly covered, rather than extending the lore of magic (e.g. there were some good ones on use of different reagents for casting, that inspired new character concepts). There is probably a way to revive this sparingly but I think this comes after other bigger issues are resolved:
There has been a lot of dilution of the tower in the last few years (decade?), again as outlined by previous posters. I personally enjoyed it more when it was a wizard's tower with visitors from outside that, with a legitimate use of that high intelligence for study RP behind closed doors. Very often, innate and martial classes have been lumped in the same space. A wizard safe-space is not always detrimental - it can help form a sense of cohesion and sense of identity, onto which RP with a wider group can adhere.
The library, once a trove of tomes most players outside the tower had to work hard to access, has lost its air of mysterious forbidden knowledge. Equally so for spellhold, when major plot artifacts like GENESIS were housed there, even under dark players would run huge quests for a peek at it.
In terms of the paladins, druids and elves, a safe-space of just the upper floor was enough that we had a mix of good, neutral and evil (if mostly lawful) alignment.
The forums are often awash with good vs evil topics, but in the case of the tower, gating out chaotics and maybe even law-chaos axis neutrals somehow from a given floor might be a nice experiment.
I've not played a wizard in a few years now, but I understand from the forums that they have lost the arms race against the many new classes. This loss of reputation as a class worth playing is probably having an impact too, as wizards are the core of purist book-tower RP.