I don't hate WotC, but I am bored with many of their offerings and uninterested in others (yes, there are differences between these groups). I've been gaming now for 30 years (well, 30 years come Labor Day) and have moved far away from my early grab-treasure-from-dungeons days. WotC represents vanilla gaming to me -- fine in its own regard, but not nearly as interesting as other offerings.
WotC puts out the core rulebooks. Good. That is what all the D20 stuff branches off from. As such, they are providing a framework. Then they have splat books for the various classes, most of which feel boring to me. Just nothing to really get me going or excite me. Not bad, just not very flavourful. Then they have Forgotten Realms and Eberron, neither of which is my cuppa in the slightest. I'm sure they are great for others, but not for me. Too magical, too over-the-top for my tastes. Most of the D20/D&D monsters annoy me - they do not feel mythological or legendary in the least, but more like constructs set up specifically to get around particulars in the rules, creatures created because of a loophole rather than because of an organic feel. I have always loathed the planes and the Great Wheel - they just annoy me. And then again I tend to prefer low-level play, thus any product aimed at anything much about 10th level loses all interest for me. And, as I have said many times, I got into rpgs to get away from miniatures. Due to this the over-emphasis on minis and boards really, really cheeses me off. And the notion of "collectible" minis, rather than individual offerings, just feels like a bad marketing scheme, rather than anything aimed at helping out the customers.
I felt that 3.5 was a mistake. Like many in the vocal minority, I felt it was indeed a half-a**** edition, not really a full expansion. Some of the rules changes were good, others were bad, many were of no serious consequence. But due to the change a lot of 3.0 material became "outdated". Yet even in the wake of this many of those who love WotC get highly annoyed when talk about 4th edition comes out. Personally, I feel that WotC brought such talk on themselves simply by releasing 3.5.
Now there are other companies out there that I feel are producing new, highly flavourful, and interesting material. WotC, by its very nature, has to play things a bit conservative, not moving away from Vancian magic, the core races, and the rest. This is not bad, simply an observation. A company like Malhavoc or Green Ronin, however, is free to play around and experiment a bit more. In many ways they have to push the boundaries more; if they do not, they are simply going to be lost next to WotC and its marketshare. Many other "3rd Party" companies have folded or thrown in the towl on their D20. Why? Because they produced nothing distinctive, nothing that really pushed the envelope. The successful "3rd parties", however, are working in the shadow of WotC - they are succesful because D20 sells well. They will always, and necessarily, be lower in their sales simply because they are offering variants on a highly successful core product. Variant products are almost always less successful. Still a product like Iron Heroes or Hamunaptra will always excite certain people looking for something outside of the ordinary offerings.
So, no real hate here. No real love either. Judge that as you will.