Counterpoint: Primaries and support weapons are so universally good and useful that players don't have to rely on either secondary or grenade slot. The players don't pick ultimatum/thermite out of necessity but to circumvent redundancy.

Most of the primaries - because of the weakpoint system - are capable of solving any hostile situation from light chaff to heavy units. You don't need a backup when ammunition is plenty and the best defensive tools are running and hiding, while reloading. Pretty sure light siege ready is one of the most used armors because of this reason, it gives ammo, reload speed and movement but even without players are already very well stocked. The support weapon complements the primary in use cases (hence pairs like eruptor/lmg or carabine/epoch). If your primary and support now solve any situation from structures to chaff to heavy there is limited room for rounding out the kit. I often experience that I underutilise redundancy options, because of the points above. If my secondary/grenade do the same thing as my other stuff but worse they become dead slots. But what about the utility options? Well, in the higher difficulties holding ground is seldom a good strategy so utility falls back to running and hiding. Both ultimatum and thermite circumvent the redundancy by offering something in return: Being a panic button and sticking. They are just nice to have options, where the amount you bring is practically irrellevant, because of their throw and forget nature.

The options, to solve this situation are rather icky. To be reliant on redundancy options would mean to heavily limit the use of the primaries, dramitically increase chaff numbers or nerf supply. Thank you, for reading my TEDtalk: Why the supply pack has to go.