Grenadiers are a 240 unit where each entity performs for 60 and reinforces for 30.
Paratroopers cost 380 to deploy but actually perform for 336mp (28*12) since they reinforce for 28.
Each
para entity deals more damage than a single
grenadier entity (and that's without any upgrades).
So they have a higher mp pool and deal more damage entity wise(and in total of course) at nearly every range.
Now let's compare other squads (paras perform for 336) :
Guards perform for 330, logically the should be much better, or paras should be worse.
Obers perform for 400.
Falls perform for 380 (60 mp deployment cost).
Shocks perform for 390.
Objectively, for what they do, they should reinforce for more mp since they are not in line with the other elite infantry. Of course they are doctrinal, but so are Guards, Shocks & Falls.