Over engineering these parts is not a negative! The cost is negligable, the bonuses are quite high.
I would contend that whilst cost is probably negligible - but weight may not be - If youre butting up against weight constraints then excess weight in the form of road wheels and associated systems will be less than ideal.
I would argue the trade off is worth it though. More so if you operate them as mixed fleet** so you can tailor the deployment eg Strike brigades sent with 1 or 2 Squadrons of Meduim weight armour - which when the follow on armoured brigades arrive can be up armoured in a few days to heavy Armour -
Arguably weve already half done this Warrior was designed from the outset to have a basic peace time config that was lighter and thus cheaper to run the fleet and have the remaining protection added before active service - thus everything was configured for the higher weight (rather than the side panels etc being additional protection) -
Obviously that approach is less than ideal in this context -