Oh man, I feel so the opposite (of course, to each his own.) To me the platforming is fantastic, especially in mid-fight. It adds to the thrill because you can do a lot of jumping from platform to platform to evade shots, double-jumping and staying above a lot of the fray. Plus they have those jump-lift force fields you can use to launch through the air.
Those were some of my favorite parts of Quake 3 too. The maps where you could spring off a jump lift from one end of the map to the other, shooting at people as you soared through the air...
I don't object to platformers per se, it's just that it's really not what I expect from Doom.
Also, I actually liked the (much more limited / less frustrating) platforming mechanics during fights, that just gives you more freedom of movement. Freedom of movement is good and Doom'ish.
It's the part outside of them, where you have to hop around in silence just to get somewhere, or get to a juicy item, that's objectionable - because that part is less about freedom, and more about railroading ("No, you HAVE to jump onto that moving train to proceed... and sorry, the last checkpoint is before that fight that you just have - hope you like replaying it if you fail the jump.").
Watching some of the better play-throughs shows it pretty well: https://youtu.be/P6J352J_RG8?t=10202
Those were some of my favorite parts of Quake 3 too. The maps where you could spring off a jump lift from one end of the map to the other, shooting at people as you soared through the air...