There should be a spawn menu like in battlefield 3 which allows u to customize equipment and them spawn. Many times for eg u have to go to the toilet in between an intense point and crysis 3 just can't be paused in multiplayer, but in battlefield 3 after dying u can remain in the spawn menu and not spawn till u return.

Therefore it's an important function of having a spawn menu

That is correct.
There should indeed be a spawn menu.

TBH, the MP is sadly turning out to be something where a spawn menu is practically useless.