Its simply all about the $$$'s
Imagine lost sales in making all top equipment open to Legend at whatever level.....
Once you have the top equipment theres no monies left in you, only in ball sales.
They obviously hope Legends on the way through the levels will spend on the new equipment as they get to the respective levels.
Gotta say though, if they can make legend at say level 40, do they actually need the top equipment ?