Boosting regulators are common, but there are efficiency tradeoffs, since: a) boosting regulators consume energy, b) boosting regulators with a sleep mode (so you're not spinning the wheels 24/7) don't start up immediately.

Two 0.9V alkaline cells can still power most microcontrollers, especially in sleep mode, and red LEDs will still light. If you really need higher voltage, than the boost is the way to go.

I previously worked off of an MSP430-turned-EFM32 product which had a MCU+radio lifetime of 5-7 years on 4-AA cells (two paralleled). Most switcher solutions we looked at wouldn't have netted a measurable increase in runtime due to the much higher sleep currents in those units compared to even the MCU.