I do understand that it is very convenient, but it gives too many opportunities for abuses.
It does not create any more opportunities than there already were. The difference between holding ctrl and left clicking and right clicking and left clicking is virtually nonexistent for autoclickers. Autoclickers are against the rules anyways, and they wouldn't really feel a difference due to this change.
You'll still be able to power train in about the same amount of time, but you have to plan dropping items more carefully. You can still drop an item and click on the skilling resource quickly after and lose no tick.
If you interrupt an action you'll lose time. You'll basically have to predict when you get a resource and then drop it immediately and click on what you're gathering from to not lose ticks. This is humanly possible, but will be far from convenient or consistent.
You gave us a wonderful feature that made powertraining a method people would actually consider doing and now you're taking it away, please reconsider.
you can always use ghose mouse to record your mouse dropping stuff and change it to high speed, which result on dropping the whole inv in less than 3 seconds.
This is against the rules.