Agree with you about the 30% cut, and honestly those systems aren't that expensive to develop / deploy if you're doing it on the scale of a few moderate-volume titles - for years we were hosted on a $10/month Dreamhost account, and still had excellent uptime and an online store that was fulling orders automatically within seconds of their being placed. (and nobody trying to push our customers into paying an extra $10 for "Extended Download Service")
The thing that makes me OK with paying 30% on iTunes at least, though, is that enabling people to buy something with a single button tap seems to have a pretty big psychological impact; there've been many many cases of companies making tiny tweaks to their shopping carts to remove a step or two and seeing sales skyrocket as a result. In Pleco's own history, when we switched (in early '04) from making people wait a day for us to check their orders / send out their registration codes manually to fulfilling orders instantly on our server we saw a very big bump in sales, one that couldn't really be explained by anything else (this was during the ill-fated Berlitz Phrase Books experiment, but the sales bump applied to our Chinese dictionaries too, in spite of the fact that they hadn't been significantly updated in a year and wouldn't be significantly updated until a year after that).
This is also one reason why I love the idea of In-App Purchase, since even now some of our add-ons - Tuttle for example - are small and cheap enough that they're exactly the sort of thing that someone might buy and enjoy if it were made easy, but would hesitate about with as complicated an ordering process as we have now (go onto Pleco.com, discover you have to log into My Orders to order add-ons, search vainly for your My Orders password, request a new password, wait for that e-mail to arrive, log in, find the link to order Tuttle, go through multi-stage checkout procedure, download keyfile, consult instruction manual for reminder of how one goes about installing these darned keyfile thingies, fight with HotSync Manager for half an hour and finally after all that get to enjoy your new dictionary). Depending on how well Microsoft's application store turns out we might even think about listing Pleco for Windows Mobile on there, in spite of the fact that we can sell software for Windows Mobile without it.
Mandatory phone-home is nuts, though; either you render your software unusable without a network connection by refusing to start up if you can't connect to the server (so good luck if you want to, say, practice Chinese on an airplane flight to China), or you allow it to start up if it can't connect and thus enable even the most obtuse of 11-year-old computer hackers to break it by putting his/her phone into "airplane mode" whenever they want to use it.