I'm guessing the full price on PC is because the modding community could easily rip the DLC content out of the iPad version and give it away on the PC.
Also charging more money might make them more money. However, doubt they'll have as many takers on PC as iPad however - maybe in a year or two (see the thread on discounts and steam).
BG1 is dated and grainy. I didn't like it at first and only paid attention after playing Icewind Dale and my best friend was really into BG1. BG2 was great! but replay was hurt by always having to go through that opening.
What folks are saying about additional content is spot on. What differentiates a cRPG from any other game is depth of content; not mechanics. However, this content must be built on top of the mechanics so its extra work, and extra cost, but provides depth over mindless twitching.
For folks who never played it due to mod issues, why not play it without the mods?