Why shouldn't I brute force PWM?
The three disadvantages are Power Consumption, tying up a Timer, and interrupting other code. If you don't care about low power modes, and have no need for the timer, and have no critical code that can't withstand a few clock cycles to service the interrupt, there is no disadvantage. Some projects are fairly simple, and don't take up a tenth of the power of the microcontroller, so don't let anyone tell you you are doing it wrong by taking advantage of the timers like that. Software PWM is fine if it fits your needs.