Impressioning is definitely a good skill. Necessary for a locksmith, and helpful for a picker. Sometimes you just can't pick a lock for some reason or another. Having an alternate Non-Destructive means of opening it so you can take it apart, make a key, actually use it to lock something, and/or attempt to pick it again is very helpful. Hobbyists being the main lock reclaimers, may use this skill just as much as a smith might. It all depends on how much you want to pay for practice locks, etc... It's nice to have a key, it helps to prove ownership in some cases and it will let you open a stubborn or dirty lock for servicing so it will pick better.
It also helps you learn a lot about locks. You have plenty of time to think while filing and wiggling the key, hehe!
If you want to sell, trade, give away a practice lock or two, it helps to have a working key as well!
The pyramid learning method sounds like a good way to go for impressioning as Randmguy mentioned. Wish I learned it that way. I haven't even attempted to impression a medeco! That might be a good topic for a new thread!
Give it a try!