Yeah of course that is the best to have. Who wouldn't want a player who is legendary in every skills?
Yes, but that is overly beyond my point...
What I'm trying to say is,
for me, secondary skills are still worth training... Height may be a factor but not that much to stop other managers in the BB world to not train secondary skills... The added option in the tactics page to assign a certain player to guard a certain player makes training secondary skills easier... For example, I want to train my PF in his OD, I can put him in the PG spot and yet, he can still guard the opposing teams' PF... Another example is you can train JS or 1 on 1 with bigmen by putting them at SF and PF and make them still defend PFs and Cs... Training JS in the SF/PF spot also brings secondary pops on IS...
We can have equal guards or equal bigmen with our opponents in terms of their primary skills but by training the secondary skills, we may just have that little edge to beat opposing teams...