It may be a waste for you, and I respect your opinion... But definitely it's not a waste for me. I don't have unlimited space in my house to have several ready to run PCs from different eras, nor I have money to buy one PC of each era (even if they are sold for only 100-300 eur each). So for me emulation is quite handy. Not perfect, of course, but for most cases it comes close enough, specially 86Box and PC-EM.
Also, for developing new software for old machines, emulators save a lot of time/money/space, three things I'm not plenty of. I just cannot have a real 386/486 for compiling and an XT for testing, running at once while connected through a local area network, I just haven't enough space. I live in a great European capital, and we have beautiful monuments, but the price we pay is having a smaller space to live ;-)
I own, as I said, a PS/2 Model 30 and a Turbo XT clone, but I can only have one of them active at a time. I don't usually compile on my PS/2 or my XT because it's desperately slow. Yes, I know in the 80s had to be done that way, but programming for old platforms is a hobby for me: I don't have 10 hours a day to develop my game, including the dead time waiting to compile, so I run my compiler on DOSBox at 10000 cycles (more or less equivalent to a 486DX-50Mhz), and run the result in another DOSBox window at 550 cycles, to see more or less what would be on a PS/2 Model 30. If I want more accuracy on the result, I test it on 86Box and, finally (and rarely), on the real thing. So I can program like it is 1991, without the need of another bulky computer I cannot have in my space. I can assure you that my software, programmed via emulators, runs perfectly on my real hardware.