It's not really that much harder. Plus it fits my play style better. Even before I switched, I would still use any green or yellow letters in subsequent guesses.
In some ways it makes the game easier by narrowing the possibilities. If you know the third letter is an "I", why waste guesses on words where the third letter isn't an "I"?
Sure, it takes longer to develop a guess but by using the letters you've already revealed, you're sure to always have at least those letters correct. Then it's just a matter of putting them in the right positions and guessing correctly on the remaining letters.
Volty's method works well for him, obviously. But I couldn't do it that way. For instance, if I start with ALIVE and I get a yellow E and a yellow L, I couldn't bring myself to throw SCOUT out there on the next guess. I'd go with LEVEL and see what that gets me.