I don't think it's easier. You can't find the #@! dos drivers anymore. It's hard to find config files for '98 now.
That would be a problem if I were using newer hardware. However, I'm using a Duron 600 with built-in AC97 sound. AC97 DOS drivers are really easy to find. Then I used CuteMouse drivers for my trackball. Those are the only drivers I need. I have no need to network my cabinet, but it is possible to do.
I agree that dos would be simpler, but man it's a pain finding and using all the ram in a new machine. Dos can't handle the big files.
I'm not sure I understand this one. I have 160mb of RAM configured without a problem. It's a one-liner to get that working. I think DOS (at least FreeDOS) will let me use up to 512mb. To be honest, even 160mb is overkill for my hardware, and I can play everything up to Street Fighter II or so without issues.
Can you even config a USB lightgun with Dos?
Not sure because I haven't found one of those that's not too ugly for my cabinet.

Actually, I've never even used one, and have no real interest in them, as I can't think of a single lightgun game that I like...
USB support for keyboards & mice under DOS is dependent on the motherboard. Some of them will allow it and some won't. So if the lightguns are treated like mice, the same rule would probably apply.
I gave up on it. I got AdvanceMame to play pacman, but it couldn't find the right sound driver.
I found that if I left AdvanceMame on 'auto' for sound, it wouldn't work even when I had the right drivers installed. When I configured it explicitly to use AC97, it worked.
If I were using newer hardware, I would use something else. Windows is definitely better at handling the newer stuff. But for anything 600-700 Mhz or less, I wouldn't bother with anything other than DOS.