Performance may not matter that much, depending on the application. I've got some arduino capable boards monitoring temperatures once a minute, but I'm using lua because the documentation for my board was less handwavy for lua than for arduino (it's an esp8266 board; the c environment is a little weird).
If performance doesn't matter, then most likely this is a sign of using too powerful hardware for the job. This is ok in a hobby project, but if you wanted to produce and sell these on mass market, then your competitor would get a smaller board with a less powerful chip and win by the price (or earn more per unit sold).
True, though wifi and ethernet are quite demanding, so any uC capable of either will most likely be "too powerful" for things like doing simple I2C/SPI communication with a sensor or five and relaying it back.
