I think that's too much of a blanket statement. Maybe things are currently not as entertaining as they were three/four years ago but almost all of that I would attribute to some degree of oversaturation (which is one of TS' points- too many cards). That said, UFC has a lot of talent so if it can justify putting on many cards, it should. They just have to do a better job of building interest and marketing the lesser known fighters.
2010 is a looong time ago. Using that as a cutoff is problematic because one of the points seems to be that it was pre WMMA and pre-smaller weight classes. But there was a reason why WEC was widely considered an awesome organization to watch on almost any given card. The smaller guys brought it- with exciting, fast-paced fights.
think of bouts like DJ vs. Uncle Creepy, DJ vs. JoeBen I and II, Faber vs. Cruz II, Dillashaw vs. Barao, Garbrandt vs. Cruz, Mendes vs. Aldo I and II, Aldo vs. Hominick, McGregor vs. Mendes there were a good number of 125/135/145 UFC fights that were awesome to watch.
Not to mention- the post 2010 integration of the WEC led to the inclusion of guys like Bendo, Cerrone, and Pettis into the UFC. How many entertaining fights have they been involved in?
Hell, bringing in Strikeforce guys happened after 2010 too. Rockhold, Jacare, Romero, Lawler- a bunch of still relevant fighters who had great performances and entertaining fights in the UFC.
I'm a fan of WMMA as well. So I don't think the inclusion of, hell, one or two women fights on a given card is a problem at all. If people's issue is the notion of a woman's fight that doesn't deliver headlining, well it happens. There are going to be dull fights from time to time.
Basically, I don't think we can look back on any period and completely say that was the golden age. MMA is still so relatively young and it is tough to make that type of assessment yet. Are some of the cards today uneventful by and large? Yeah. But that was the case six or seven years ago too.