1) If I buy a disc in a shop I still have to spend hours downloading the whole game via Steam's servers - thats f'd up; don't they store the game on discs anymore? If you have to go through Steam anyway, why bother having discs at all?
That's just devs using Steam to deliver day-one patches, complain to the devs. Pretty common practice though these days, it can be a month between going gold and release day, there are bound to be updates they want to push on day one. If it's downloading the whole game you're doing it wrong.
2) Downloading games via Steam (or others) not only takes hours but it also costs me more money in hefty bandwidth usage
Well downloading large amounts in a DD environment is pretty much a given. This is more of an issue with DD in general, not Steam.
3) It discriminates against those who don't have internet/ don't have easy access to it/live in internet black spots - they cant just buy the CD instead cos the disc still needs to download through Steam!?
As above, you're not "downloading the CD" through Steam, these are day-one updates put through by the devs which can sometimes be large. Steam does seem a bit weird when it comes to starting offline, not sure what is up with it.
4) Contacting customer support is really hard, there is no direct phoneline or postal address (unnacceptable IMO), all they have is some lame email system where you send an email and pray they'll get back to you some time in the future - I've sent emails to them in the past regarding tech issues and had no response from them - they're customer support is very poor IMO
Yes it is poor and not really acceptable for such a huge company and a service with ~30 million accounts. I've never had to use it myself but to just offer a ticket system is bad.
5) Tech issues - I share a Steam account with my younger brother but sometimes I log in using his account and it blocks me - the username & password are correct and he isnt on at the time but it still blocks me and doesnt even explain why!! AAAAAAAAAAAARGH!
For security reasons I imagine. Steam accounts are not designed to be shared.
It also outright barred me from playing Civ 5 for ages by cutting me off in the opening intro - nothing I could do about it, although last time I checked I can access it now
How do you know this was a Steam issue? Could have just been a technical issue with the game. "Cutting you off"?
6) It's never good to have a company cornering the market like Steam has - I try to avoid them but their damn logo is on pretty much every game I look at
Well, there are plenty of other DDs around that seem to survive well enough. Yes Steam is the market leader but that's because they're the best at the moment. Someone has to be top.