Monero has evolved considerably over the years, and some of the "legacy" and historical facets prove to be sub-optimal (payment IDs, emission curve, mixin 0 transactions on the blockchain, hardcoded blocks due to attacks, etc).
Considering that Monero is in of itself an exercise of the philosophy that its better to re-code and create anew (as opposed to improving upon - i.e., why didn't Monero supporters just improve bitcoin), why would Monero stop itself from creating a blockchain without the historical baggage?
(and yes I speak of Monero as an entity for the sake of simplicity)