Having played our last few rounds of brood wars, one thing that has come to the surface is that the new areas with flying units only make the game much more centred around fliers. The fact that none of the ground unit only areas on the board contain conquest points means that players are often forced to build fliers to get these points, or indeed to stop others getting them. We are considering changing some of the old planets with conquest point areas to ground unit only, to give us more of a reason to go with ground units. Siege tanks and Ultralisks are cool, but when i can't use them to protect or take conquest they become kind of pointless. I thought the split between ground and air sections was a really good idea, i just would have liked to have seen some ground areas with conquest points on as well.

Any thoughts ?

Remember that there are a lot of new technologies and units that destroy flyers with ease. Charon boosters, Corsairs {notice that they are not on the Protoss flyer path}, more powerful Scourges etc. It's not so easy to focus only on flyers anymore.

Ultralisk: This is one of the cheapest "tanks" in the game and it can be build faster than any other "big" unit. That's its advantage. Its disadvantage is that it doesn't kill flyers.

Siege Tanks: Just two words. Collateral Damage. This ability promotes a different kind of warfare and you shouldn't think of Siege Tank as a simple brute force unit anymore. This unit is all about demolition!

Just my thoughts...

Just so. And yes, the game concentrates a bit more on flyers in my opinion, but Brood War did this on PC, too. And FragMaster already said why the ground units aren't obsolete.