I agree totally. The whole Mobile Pod app is somewhat disappointing - sound quality is good (as are, lets face it, most amp sims these days), but the number of effects is really disappointing. I'm a long time Line 6 user, have an old red UX2, and love my older version of POD Farm, but I totally expected that Mobile POD would have a similar complement of effects. It's a really short list. Also, I think it should have a 2 signal chain capability - most iPads have more than enough horsepower to process.
Worst case, it would be nice for Line 6 to sell an upgrade that gives you features at least approaching full-blown POD Farm, say $50-$100, and you get 2-3 versions of each effect category, two signal chains.
As it is, I actually use Positive Grid software most of the time. Cheap, works well, and has a good starting complement of effects, and ability to buy more.