TO each their own, but to me, The Dark Tower is a masterpiece of the imagination and what makes it so much so is it's part in King's universe/bibliography. I personally don't get how someone could hate King or hate horror and still love The Dark Tower. Stephen King to me is the master storyteller of the last 50 years. That is why I can't imagine enjoying the series (as badass as it is) without being able to enjoy all the connections of it's characters and goings -ons with the rest of his bibliography. Sure, some are small, but their subtly is what makes them so amazing (like the connection Insomnia makes to Pet Semetary, thus tying the latter to the main universe/series [no one ever seems to talk about this one])... but others, like The Stand, IT, Insomnia, Hearts... Salem's Lot, The Eyes of the Dragon, Talisman/Black House, are massive and extremely important to the reading experience if you ask me.
I'm sure it reads just fine on it's own, as it is a wonderful series (including The Wind Through the Keyhole, which i thought was beautiful and the best book of that year), but I promise you, you are missing out on some sweet surprises and 'oh cool!' or 'a-ha!' moments by avoiding so many of his other books. But I guess this comes back to how much of a King fan you are, as opposed to being no more than a Tower fan. But again... with me, that possibility does not compute. Lol.
Also, I am not a fan of 'reading orders'. As far as I'm concerned, the only order anything should ever be read in is 'order of publication' unless explicitly suggested otherwise by the author because there was some screw up in when his books were published compared to written or something. I suppose when it comes to The Dark Tower, even though I only started reading King in the mid 90's as a teen, I was fortunate enough to make the decision to read the majority his books in order of publication, so I didn't feel like I was missing out on anything.
All that being said, I really need to get caught up on some of his 'recent' work... recent being stuff written post-Tower.