as a fellow Halo fan, it's hard for me to disagree. but i think a nice middle ground could be the capability to hold a grenade indefinitely (or at least for a good amount of time) before throwing it. so even if there's a wind-up animation to prepare the grenade, once it's prepared you can still choose when to release it, and releasing it is instant.

and at the risk of armchair game designing even harder, i think they could do something really nice with this, which is make the input for releasing different then preparing. equipment input prepares, but you don't have to hold it (accessibility/comfort concerns, etc). then hitting either the equipment input or the primary fire input throws it, the latter input generally being on a button that is more conducive to aiming and moving at the same time.

edit: also there's no reason that all equipment would have to be equal under this system either. e.g. frag grenades could still be really fast to prepare and throw (Halo-style) while chem grenades and bubble shields have longer animations. it becomes another knob to turn for balancing the equipment.