That is just a matter of competition. Companies stepping other companies just for their own good competitiveness,even if those ICOs were just looking like copy-paste projects, I am pretty sure that they could be into the ground right now when they're just copying other projects. They have their own differences not just from the aesthetic elements of their projects, meaningfulness and applicability of the project/WP itself.

In fact you had mentioned various exchange that pretty much looks like same, as an exchange or trading site but in terms of the trading volumes in each exchanges varies as X coin might not exist to another exchange while Y coin exists there.
Good question, OP but kinda misleading at some degree.