Yeast: Dry vs Liquid

Hey guys,
I've been brewing for about 3 years now (2 years AG) & I have always used liquid yeast. I always hated making a starter, mainly because my brew days just happen when I have the time. I started using 2 smack-packs per 5-gallon batch to make up for lack of starter and have made awesome beer doing so. Although now I am tired of buying $12 of yeast for every batch.
I have noticed there are a lot fewer selections of dry yeast vs the liquid; why is this? If I use a dry yeast, say Danstar Nottingham Ale versus Wyeast 1272, will my flavor profile be that much different? Why is it that so many liquid yeasts suggested for certain styles can be replaced by a single strain of dry yeast? I know this is elementary to some, but I guess I need schooling. Thanks...

Dry yeasts are difficult to properly formulate to get them to perform suitably. Each new strain takes a lot of work to be able to get it good enough to sell, and there are no guarantees.

The selection of dry yeast is slowly growing, but eventually it should be large enough that a *truly* suitable strain should exist for all but the most minor and obscure styles. Just not anytime soon.