|Why? Short answer, because I want to.|
Long answer, I do like Windows 98, I can get online with it, it does or can be made to do just about everything I need/want it to do. In my opinion, the only thing that more modern incantations of Windows really have to offer is the NT Kernel. Although, if you choose software somewhat carefully, the 9x Kernel is pretty good. Also, I have some old unopened versions of Visual C++ and Visual Basic, that are from a slightly earlier era and I want to do some programming. I actually want to test the stuff I compile on something older.
Going a bit beyond what you're asking, I didn't like the direction Microsoft took with Windows after Win 2K. The calling home (WGA, WPA, legitcheck), the babysitting (Security Center, System Restore, et cetra). Given what I said, I think you can imagine how I feel about Vista and 7, let alone 8. I don't want you to think that I'm a pirate either, I have still-in-the-box versions of Window and Dos! In fact, I opened Windows 98 SE just for this computer. I'm toying with the idea opening my NT 3.51 box to install on this thing. I don't despise XP, but when I open and install it, there's going to be some taming going on.
As to the VM(s) -- I appreciate a VM for what it is. I sometimes test out ReactOS on one. I wouldn't call DosBox a VM, but it's sorta in the neighborhood. I like having it (DosBox) on my later NT/Linux installs for old games and software. I don't like using VMs for long periods of time, they can be a little slow and hog a lot of resources and frankly, 98 SE is modern enough that I don't really see the need.
Obviously, these are just my opinions, take 'em for what they're worth.