But that was never what was really going on, all these were the same CPU design, except that when yield rates for the FPU weren't so good Intel disabled it and sold those as the 486SX. When sales of the 486SX outstripped supply of dodgy FPU 486DXs Intel removed the FPU altogether from new ones. Meanwhile the 487DX wasn't "upgrading" anything, it just disabled the 486SX and replaced it with a full CPU.
A customer is buying X features for Y dollars. It doesn't matter if certain other features are there and disabled, because that's not what the customer paid for.
Software does this all the time as well. Say you get the first three levels of a game for free. You have to pay to get an unlock code for all ten levels. Is it unfair that you really got the whole game for free and that you are being kept from accessing it unless you pay?
If you get the features you pay for, then the transaction was legitimate. Fin.