Kirk wore down last season as you pointed out and only started 78 games behind the plate. You even now just admitted he doesn't have the build or body type to catch 130-140 games per season. I think we can both agree with that.
I'm not sure Moreno comes with the same question mark. Yeah he'll wear down over a full season as well, but I don't think he'll have an issue starting 130-140 games behind the plate, as long as he stays healthy. Probably why teams like Arizona valued Moreno more than Kirk, but we don't really know.
Blue Jays definitely have benefited having both Jansen and Kirk in the fold like you said. With Jansen, you don't have to worry about starting Kirk over 100 games. You can still keep him fresh and his bat in the lineup as a DH, and visa versa with Jansen who has had his own issues of staying on the field over the past several seasons. So overall, Blue Jays are in a good place with both Kirk and Jansen behind the plate over the next 2-3 seasons.