pickit2 project
funnynypd PICkit2 circuit has the 3.3V clamps so it can program 3.3V PICs just like a true PICkit2.
Adding the 3.3V almost doubles the parts count and complexity of the PICkit2 plus most 3.3V PICs are not beginners PICs (24 & dsPIC33 mainly) those 3.3V PICs often don't come in DIP packaging either.
5V covers the most commonly used PICs from 10F, 12F, 16F, 18F & 30F and the bonus of 5V EEPROMs (the PK2 standalone software programs many EEPROMs)