Because you can't be both.
You can't eat all the cakes in the world and remain skinny, unless you're me. You can't have the perfect pvE build but at the same time having the perfect pvP build (templars get close, though).
On the other hand, nobody is stopping you from having pvE armor/staff and having pvP armor/staff.
Why would you level hp/mp coils in order to pvE, if you could do the same with hp/mp leech even more effectively - whilst still maintaining the required skillpoints for a pvP build - but why would you get absorb on a pvP staff? (if, by all means, you're using a staff in pvp to begin with)..
So, basically, if you're planning on leveling count blow, why not just listen to others their advise?
..and why lose points in skill resets, when you can just build your tree good from the get go? But that's just me, ofc.
Take it as you want - you have the advise, if you're rather stuck with a half-so build - be my guest. It's yours, not mine.
I sincerely hope you enjoy it as much as you can - but requesting more skill points just in order to level everything is a no-no for me, and I hope so for the dev's as well.
Cheers
Eagle
over-and-out