Well, I tend to agree. Most server owners seem to be under the impression that slapping a bunch of plugins together and building a nice looking hub or spawn is enough to provide some decent gameplay, while in fact there really isn't anything special like a specific design on the server at all. It's just a collection of plugins, which you could easily have put together yourself. Most don't even seem to bother customizing it. Well, maybe apart from all the annoying advertisements you get to try and motivate you to vote for them or even better: buy custom items.
However, I don't think it's the servers which became worse, it's simply that the whole server "market" has become completely oversaturated.
There are also plenty of servers which have come of a good age (think 3 - 5 years old) and are still quite enjoyable today. Of course, 'enjoyment' is in the eye of the beholder, as always. I'm still very much into vanilla'ish survival play so a decent survival server is already enough to get me entertained, but I can well imagine that this might not apply to other players.
But to answer: I obviously prefer todays servers, because the older servers won't provide you with all the new stuff we have today.