Why am I bringing this up? Here's an example, a very superficial simple one to boot:
To build a reaper, you need a supply depot + rax.
Supply Depot
Build Time: 30 → 25
Reaper
Life: 60 → 85
Build Time: 45s → 42s
Movement Speed: 3.75 → 2.95
Attack range 5 → 4, attack period 1.10 → 1.33
Your proposed changes: supply depot (25s) + barracks (46s) + reaper (42s) = 113s
LotV live = 30 + 46 + 45 = 121
Net -8s
To build a mothership core, you need: pylon + gateway + cybernetics core.
Pylon
Build Time: 25s → 30s
Cybernetics Core
Build Time: 50s → 45s
Mothership Core
Build Time: 30s → 50s
Shield and Life: 60/130 → 90/90
Armor: 1 → 0
Movement Speed: 1.88 → 1.41
Removed general weapon and Time Warp ability, Mass Recall energy costs 50 → 100
Photon Overcharge: have been changed to a weapon activating and using directly by the Mothership Core. Drains 3 energy per 1 second and can not move when activated. Damage dealt 35, range 6, attack period 1.65
your suggestion = pylon (30s) + gateway (46s) + cybernetics core(45s) + mothership core(50s) = 171s
LotV live = 25 + 46 + 50 + 30 = 151
Net +20s
Current LotV builds have the mothership core coming out exactly as the reaper reaches the protoss main on most maps.
Your proposed changes will have the reaper have an additional 28s of free reign.
Ok, but you can build an adept or stalker to deal right? You've shifted the 38s vs 42s of stalker vs adept, so just for argument sake, say you didn't touch the build times. The nerf on the pylon+cyber core time is still an additional 20s. The reaper + supply depot is still 8 seconds faster. Still 28 seconds difference.
I'm doubtful the move speed nerf on reapers will cause it to take 28 more seconds to reach the protoss mineral line. The reduction on range does not change the interaction between worker vs reaper. To further complicate the problem, if the terran proxies the reapers... then the protoss just dies 100% of the time?
This is just 1 example. You've made sweeping changes that drastically affect race+unit interactions that need to be given more thought.