If the game keeps developing as it does with more worlds, new gear, new spells ect ect. Having the option to retrain without spending a month worth of subscribtion really needs to happen.
Tactics will keep changing as you get different gear, new spells, higher lvls, more training points even if something like maximum pips get increased ect.
You can probably manage not retraining if you only pve but it still won't be optimal and also if someone makes a mistake and train something they later find out is not.
And especially for pvp players this is extremly essential.
Nobody wants to spend a month worth of sub in crowns to retrain and even if this doesn't get changed to you can do it with gold or aother idea would be to have the ability to retrain once a month for subscribers. The current price in crowns to be frank is a ripoff.