I know.
You would lose units such as the Hellbat which are necessary for mech to work, Cyclones which provide some decent additional anti-air and skirmish potential despite any problems with them, Vipers (which are good at helping Zerg to engage and create much healthier games than Infestors) or the Tempest which was necessary for Protoss to engage Brood Lord + Infestor back when Fungal could root.
You would also lose many fixes and improvements to existing units such as DT, Ghosts, Siege Tanks, Thors, Colossus, etc.
LOTV is much better than WOL even if some of the units added were suboptimal or have problems (such as Disruptors dealing full damage within their entire blast radius and having a long cooldown, such that they are more like 1-shot casters than Reavers). It is much better to improve units in LOTV or add/remove units and mechanics to it than to start over with the death-ball junk with holes in it that we had back in WOL.