IMO it only makes sense to have one operating system. Just as much as it makes sense for the whole world to speak one language.
Just my two cents... Just ask yourself those questions. No point insulting or disrespecting a man or company for no reason.
Gates is just a figurehead for something that is hated because it is so successful.
Therefore, we don't hate him, as a person...or at least I don't (although it doesn't really bother me that I have to shoot an effigy of his head down to win "Defendguin"). Furthermore, I don't necessarily hate M$. They have come close to their vision of "a computer on every desktop", and that has put some bread on my table. It has done even more for my brother, who has no other source of income than his IT job, and makes more than I do. I don't necessarily hate Microsoft, but I don't really like their OS. I like "Age of Empires". I like their icon set. I like their Open Charity Licensing program (but if your charity can get along with Linux or BSD, you're still probably better off). I like the online clip art, and to some extent, I like a few other things, possibly at least the idea of Windows Update. BUT ---
I don't like 'flattening' a computer because it makes more monetary sense to do so than to fix the issue --- it feels wrong, but it would be wrong to my customers to actually charge them for the time it would take to fix a really munged up Winbox.
I don't like telling people that they need a new computer because they need a new version of Windows. (That might be different if I sold computers instead of merely working on existing ones....)
I don't like the fact that the underlying OS only exists to provide me with a GUI, and that they are so strongly tied together that:
a. When the GUI "freezes" the entire system has to be taken down...there's no other terminal available, and remote access is dead as well.
b. When a segmentation or page fault, null pointer error, or other programming bug hits an application or a part of the OS itself, my system, rather than I, decides if a reboot is appropriate; and furthermore, if I instruct the system not to reboot, I'm simply greeted with the BSOD and forced to reboot anyway.
c. A hung application interferes with my ability to get work done by inhibiting app switching while the system tries to recover. This does occasionally happen with other OSes and various window managers, but by far and large it is Windows that does it more often and for longer.
I don't like the fact that sh or csh, written when I was a child or teenager, are more utilitarian than the tools built into the Windows XP command line, which was written when, since I've been married, at least, or even since I've been out of college, or even this century?
I don't like the fact that loads of processes that most users don't know about run as root. I especially don't like the fact that most users run as root, and know nothing about what not to do or allow when connected to the Internet.
I don't like the fact that for years, Windows did no ingress filtering when connected to the network. Furthermore, now that the firewall is set up "on by default" or whatever, I don't like the fact that it still won't do egress filtering or really allow me to write rules in English instead of checkboxes.
I don't like the fact that I can't read the source code without signing an NDA with the company. Not really a good gripe, because that's true with most software companies. But I can read Linus' code, or BSD's, if I want to. This becomes particularly important only about 3,289 times a year when a security flaw is exposed on the Internet and it takes 47.9 days before a patch appears on "Windows Update". OK, I'm pulling those figures out of wherever .... but anyone who deals with this from the viewpoint of supporting end-users has probably felt that way at one time or another; probably real frequently, actually.
Finally, I don't like the fact that I have to pay at least one hundred bucks to have one computer run one copy of this OS, which is superior in some respects to other OSes, but inferior, in several other rather important reasons, to almost every other OS on the globe, many of which don't cost me a freakin' dime.
By and large my few Windows systems run OK, but my other systems run much, much, better, longer, more stably, and with less babying.
I'd strongly encourage you to find some reasons why you actually like Microsoft, compare them with the reasons why Microsoft often is called Micros**t or whatever, and really gain an understanding of what you do think. Start by plugging "Why I Hate Microsoft" into Google, and read Frank Van Wensveen's rant on the subject. There's certainly a lot more to this issue than some touchy feely "let's all have OS unity" claptrap....