If poker is a hobby for you then you really don't care whether you start with $10 and build it up to $100 playing micro limits or start with $100 and end up with $1000 playing $1/$2 or higher.
If you are just starting out and you know you are not playing correctly, why would you throw $100 on a site and give it away to players you have almost no chance of beating unless the cards hit you over the head all session?
I think that playing microlimits while reading some books and trying out new ideas is a very good place to start. Learning to read the board and other players hands takes time and personally, I would hate to throw a few $100 to that training when it is available for $10 or so.
Learning and moving up through the levels as soon as you are ready is the only way poker stays interesting/challenging, though. If you were to stay at the micros for more than a few months I think you could start to see boredom setting in and causing you to play more hands, play hands farther than you should, etc.
One Key note is that IMO microlimits CAN ONLY be useful if you forget that the big bet is ONLY 2 CENTS. If you treat a BB as a BB then you can use them as a tool.
Microlimits are also great for developing a tollerance for taking the bad beats, while avoiding tilt. This can help when you move up and people actually start respecting a raise instead of assuming you MUST be bluffing, because who would raise with a good hand? (The mantra of the microlimit maniac
)
I will say, however, that it takes a concious effort to adjust to higher limit games after playing at the micros. Where you usually have odds to draw to open-enders and flushes at micros, when you move up and are 2-3 handed after most flops you will lose those drawing odds.
Just my thoughts.
I have on a few occasions taken a free $5/$10 or some freeroll winnings on a site that I can't withdraw from and used it as a side project to see how much I could build it up to, or try to build it up to the level required for getting it off the site.
OK , that is enough about that...