It's all about using the tools properly. Regen is something to mindful of as if you cast it so its still running from pull to pull then you will get initial threat making the pull that much harder on the tank and unnecessarily difficult for you as well. This heal can be clicked off but its our skill and tanks shouldn't have to constantly be looking to see if its up before they pull. Use good judgement on regen to help get through the middle of the pull but don't recast it as damage will get lower as mobs die off and the extra healing from regen is no longer needed on top of other heals.

Medica II being spread out over 30 seconds has helped a lot with the aggro issues but for things like stomps and jumps from titan you can still grab a lot of threat if you are spamming people to full with medica then having medica II do mostly overhealing. You want to top people up before a jump but during stomps and after jump having people over 50% is fine so you can let medica II tick and heal people up without the overhealing.

Cure III suffers from the same usage restrictions as medica II and medica. You have to make sure that if you are going to use Cure III that the same goal couldn't be accomplished by medica and that you need a huge heal on 6-8 people. Any time you are overhealing you really need to ask yourself if you are using the right heal because your only pushing your aggro that much higher potentially without reason.

Lastly don't use shroud until your orange on threat. This way you are cutting yourself down the furthest you can each time you use it. But if you are smart about your heals you really shouldn't even have to worry about that much either.