i think you're right on the money. the only way theyll ever do that though is if they make it so that you can only buy 1 of each type of item and then sort out all of the items to split from the same core items.
so for example how trinity force builds from sheen, stinger, and phage? well sheen has like... 3 options, phage has 2, and stinger has 2.
sheen+phage = x
phage+stinger = y
sheen+stinger = z
x+stinger = trinity force
y+sheen = trinity force
z+phage = trinity force
since sheen builds from sapphire crystal with no additional items it affects build patterns by throwing in random stats passives and actives that just get tossed or multiplied to cause a huge amount of overloaded items.
a long time ago i made a post about how i wish the base stat items :

were used to combine into every form of item in the game like this
basic items = a,b,c,d,e,f,g,h,i,j,k = 11 items
tier 2 basic items = a+a=A = 11 more items
tier 3 basic items = A+a=A! = 11 more items
combination items tier 1 = a+b=ab = 55 more items
combination items tier 2 = A+B=AB = 55 more items
synthesis items ab+c = abc = 165 more items.
fusion items A+b=Ab = 55 more items
total = 363 items.
currently there are 220-ish items in the game and yet players feel that there aren't enough. i feel that with this systematic approach there would be plenty of items in game.
also i would go so far as to even change the name "critical" to "precision" and have it represent penetration and criticals depending on the items combined with it. so for example magic pentration boots would be a AP+movement+precision. critical strikes would be penetration plus attack speed.
here is a list and description of the stats i would use - the names are changed but the stats are pretty much the same.
hp = max health
hp regen = the gain of health
mana = maximum mana
mana regen = the gain of mana
speed = the time it takes to act
movement = the rate of distance traveled
strength = a modifier for physical numbers
spirit = a modifier for magical numbers
precision = makes character deadlier
nullification = makes magic numbers weaker
armor = makes physical numbers weaker
cooldown would be speed plus spirit.
lifesteal would be something like hp regen plus strength
boots would need to be reworked since currently boots can only be bought 1 time and arent upgradeable anymore. so it would have to be adjusted so that only boots can be built from boots or something similar.