(Hey Captain Planet - good to see you and everyone else yesterday.) I agree about the Dinobots (who are boring, and this comes from someone whose favourite Transformer for twenty years was Grimlock.) But you realy believe Bulkhead and Sentinel Prime haven't had sufficient development? I think they're amongst the best and most well-rounded characters on the show (and presumably Season Three will give us even more backstory on Sentinel and Optimus's shared history.) Plus, now that we've seen Bulky and Sentinel in flashbacks as well as present-day we can see how they got to become the bots they are now. (And it turned out that the fact that Bulkhead is a country-bot who wanted nothing more than to work on space bridges was a huge plot point.) Season Two was one of the best Transformers seasons ever IMO and it brought us Wreck Gar, Swindle, Samurai Prowl, Jazz, Blurr, Wasp (kind of), Longarm Prime and Shockwave toys even if we don't get the Constructicons and Omega Supreme.
I'd be worried with the series not introducing new Transformers just because they haven't produced the toys 'yet', since then we might end up with another season of the Autobots fighting humans and a whole toyline of recolours. (Although... a toyline of recolours of Lugnut. Interesting...)