Repetition, repetition, repetition. All jokes have been made some seasons ago, so let's warm them up.
Everything that we have seen in the last two episodes has been there already. There are so few new things (despite Howard in Space - which we knew would come) that it seems that this episode could have been located somewhere in the 4th season.
When I first watched TBBT in 2007 I wondered what "weird thing" this was and liked it for its nerd-factor. But what is pushed out right now has moved light years away from its initial difference into mediocre mainstream.
Nowadays it's just getting derivatively boring . Why should people keep watching TBBT? For the warmed up jokes? Or the on/off relationships? For the seemingly interchangeable characters?
If this trend continues some fans (including me) are likely to lose something - not because it has been taken away but rather because it changed for the worse.