as dota player, i agree mostly with jinxofsin. it is true that the "flaws/bugs" are what made the games so competetive and thus popular and long-lasting. i have a story:

I bought Pro Evolution Soccer 2009. The last version i had played was PES 2006. So it had been a while since and i was very rusty. Actually i was a noob. But i remember how i did all the tutorial challenges and played like 5seasons of master league on PES 2006 before i became extremely good.
so i kept playing PES2009 even though i had this big frustration over it, because i was losing almost all the matches on master league and had restarted like 5-6 times or something. But i wanted to play it, because it was so hard! I had to become good, i just had to do that through-pass and sprint my forward like hell, get that ball and place it in the goal!!! and eventually after playing like a madman i got to this level with PES2009. Then i woke up next day and just didnt ever play it again. I had become as good as i wanted to be and there were no reason for me to keep playing, i had lost the urge to play completely! Sometimes i feel like playing it, but i dont because i know im better than the AI, there is no competition.

Here is another story:
i used to play unreal tournament 3. Became real good. didnt even use crosshair. then i bought call of duty 4. single-player was awesome! when it came to multi-player i used some days getting to know the maps, but basically after those first few days, it wasn't a challenge anymore. why? because the speed and aim in unreal tournament 3 was so sickly more "pro" that when i played cod4, i would own ppl so hard it wasnt even fun. I just ran around gunning ppl down. running and gunning, easy. too easy.

if you didnt get the points in my two stories (which are real), then i will explain: if the game is too easy, there won't be a lasting appeal. thats why starcraft is sill played 10years after in competetive gaming. thats why dota is played in competetive gaming.
maybe the flaws/bugs made the game hard, but in the end, that's what made the game "good". ofc the downside to this is, as mentioned already by other posters, the extreme hostility towards new players.

for the record: i dont want last-hitting in demigod, because the way it is designed right now (and will probably not change that drastically) is impossible to implement any last-hitting on creeps. i mean, if u play the rook, u can just walk on the grunts and they fall off the ledge lol! thats awesome!
in dota, however, the creeps are actually a threat to you early on (as in two creeps can get you down to red health). so in that case last-hitting is a fitting mechanic (because it takes more than 1-2hits to kill the creeps).
but i understand that for any long-lasting appeal, demigod will need some kind of "pro" skill usage. or very few will play it in the long run!!! i think this is the same as what jinx said about skill-ceiling....