Not sure I understand. Take for example applications in communications where you need a real time signal processing. The alternatives (custom ASICs) are several orders more expensive. I would actually say the opposite, FPGAs make short-run, high-end affordable to others that are not government or large coperations.
I feel like we're constantly spoiled by the clock speed of computers, they are good enough for so many things. FPGAs can make simple things a bear to implement, and you will just get there faster.
But there's a bunch of things where FPGAs are like discovering fire, all the discrete digital logic you ever wanted in the palm of your hand (until you have to meet timing).
You should always do the simplest thing that could possibly work…
That's giving a lot of credit! I see way more of "this FPGA could have been two logic chips and an EEPROM"
Yeah obviously FPGA's are unquestionably awesome devices, but IMO the real problem with them is they have no long tail or economies of scale compared to other device types. Having worked with them personally, I mostly believe this is because there aren't really any great cross vendor standards analogous to a CPU's ISA. The lack of interoperability absolutely destroys the ability of competition to benefit customers. I'd like to be able to buy a modern $5 part with capabilities equivalent to something like a Cyclone IV, but there's nothing even remotely close.