Hey why do people play these games on controllers and not k+m?

MGS games 1-3 are made primarily with controller in mind. And while MGS 1 is quite playable with KB due to it's relative simplicity of control scheme, MGS 2 was made for PS2 dualshock 2 controller and has an aggressive button combination in work that is hard to pull off with a flat palm on the keyboard. And also because it's pretty much just "KB"rather than "M+KB" because the use of mouse is extremely limited, even in the menus.

The first Metal Gear game was of course made to play with keyboard in mind. That's an obvious fact.

Same if they ever re-release Metal Gear 2 Solid Snake, aka the best Metal Gear game ever.

In my opinion and experience the keyboard and mouse just don't work for these games at all and are a chore to play because of how awful they feel compared to using a controller...