There is actually no incentive by Fritzing to have a created part repository, because the only income they make is supplying support to a free Fritzing.
The only reason FZ is still here is the income from making parts on request and other support - It's the same as the Linux model -, so for free program I guess we can't really complain.
FZ use would grow with a parts bin, but it might also kill it.
I like FZ because it's relativity simple, except for creating parts, but the larger more complicated CERN supported Kicad is probably be way to go if you want to future proof your learning curve.
I didn't know much about the electronic world 3 months ago and I only got involved because of the Arduino controlled EMS project "Speeduino". I started using FZ because SD used FZ, but they are switching to Kicad so I will probably have to as well - that was a lot of Fritzing and Inkscape leaning that will probably end up being wasted time for me -.