I doubt they'll ever change that now, I still miss having firebats in mp
though the Hellbat looks nice it's not exactly enough for me to justify spending full game price on an expansion pack
Except, y'know, that it adds a full game's worth of content...
The HotS campaign is as long as the WoL one and a new multiplayer (meh - it's probably just an expansion to the multiplayer - new units, gameplay changes) - the only thing that I think sucks is that you have to own WoL to get HotS when really they could be separate It's definitely a business decision rather than a technology/development one.
The problem is that Blizzard just don't ever reduce the price of their games - WoL is still £25 (on amazon) after 3 years which is barely a reduction on the full game price.
Most expansion packs just contain a few new maps or whatever (e.g. China rising - 4 maps and a handful of gadgets) - but Blizzard are always adding/rotating new maps anyway, for free.
I think the value proposition for HotS is actually pretty good.