Both effects only happen once, and should be great in Limited
Some commanders will certainly optimize the mana value better than others but say you have a Tiny Leader and turn your land into a 3/3 that eats a flier, that is nothing to scoff at
These include cards such as Alisaie (reduces spell cost), Alphinaud (draw), Archmage of Runes (cost reduction, draw), Fandaniel (surveil, direct damage), G'raha Tia (creature tokens), Hermes (creature tokens), Krile (graveyard return), and many more
Kataki, War's Wage Affinity flat out loses to this if it's timely enough and doesn't have the Galvanic Blast, and can still struggle even if the timing is suboptimal
Queen Marchesa is, too
While its pricey at six mana, Molecule Mans colorless nature makes it immensely splashable