Well, the people that do choose iPad or iPhone, seeing as both are the ultimate casual platforms. People who want hardcore games with a lot of depth choose PC instead. Simple as that.
Glad you like it. I'm really surprised how a game that good is so underrated in the Appstore. Maybe it is because of the rather steep original price. Yes, I know the controls need to get used to, but it actually took me 10 minutes to do that. Yes, the difficulty level of some encounters is so high that you will need lots of replays to work out the perfect tactics. But that makes the game challenging and makes victories even more tasty Plus the game has beautiful retro styled pixel art graphics, lots of content and it is universal so all iDevice owners can enjoy it now. It is really a nice breath of fresh air compared to all the casual games out there. Devs, please remember that hardcore players that look for something more challenging than casual-15minutes-short-session games are also a big part of this gaming community. Keep that in mind
Another simplified hearts of iron for ya. World in war: http://forums.toucharcade.com/showthread.php?t=76835
I think rogue planet is good, I am not sure if it is light on strategy for you, it had its intense moments which gave me goosebumps I have Battle for wesnoth too, never got to playing it though, I kinda do not like the hexxa layout
How about Romance of the Three Kingdoms? It's for iPhone and I'm not sure if it's available on iPad, but that might be considered a bit more "hardcore".
"Blood & Honor" is a good Risk clone w/ multiple maps and objectives, plus online play. I daresay it's better than Risk. "Highborn HD" is a fun fantasy turn-based affair. Highly ignored despite it's quality.