Windows 3.1 also hit a sweet spot for OEMs; with RAM becoming larger and cheaper, and 486 PCs delivering speed. That was when PC games that targeted Windows started to arrive in reasonable numbers.
Microsoft also made a big push at this time for preinstalled Windows to be considered the baseline configuration instead of treating it as an optional upsell. It probably also didn't hurt that 3.1 was when Windows was seen as having properly matured (cf. Vista vs. 7). Basically, the 3.1 era was when Windows went from being a novelty/luxury to being everywhere practically overnight.
Works 2 was released for Windows a year earlier, but I think the 3 release was what really shone. IIRC, that was the version I had bundled with our home PC:
I don't think any of the common suspects targeted Win 3.1 (or its beta version of Win32). Most of them shipped with a DPMI kernel (Dos4GW being common), which Win3.1 happened to also provide, but I can't recall if, say, DOOM even ran under Win3.1 at the time as 4GW did a lot more than DPMI.