I agree about Tomochin's speech sounding like a goodbye speech; I think her popularity started to drop once she started to focus more in fashion, because she started to give a more grown-up aura which despite being sexy, is not as playful and cute as an idol is supposed to be (according to some people).
She still has a lot of support and I'm happy she's aware of that, and maybe she had considered graduating before, but after Acchan announced her own, she (and maybe many others) realized that there is a time when they have to take care of themselves and rely in their own name to fully achieve their dreams.
I'm happy of seeing her more relaxed than in the 2011 elections, she is growing up and that's wonderful!