I'm not sure if it me but I notice that if I am casting another/attack I can often not press another skill to fire off during that same exachange.

To be more specific in this this example:

1. Holding down left-click auto-attack
2. Try to cast Winter's Grasp/Solarfall/Plagueburst
3. Nothing happens
4. Stop holding down left-click auto-attack Doing nothing now(example: no life leach keeping me alive)
5. Try to cast Winter's Grasp/Solarfall/Plagueburst
6. Now the skill cast

This is jarring coming from other ARPGs where they allow this sort of behaviour such as Diablo 3, Last Epoch, and Path of Exile.

Players should definitely be able to cast other actions in general similataneously during other actions. Obviously some balancing may be required but in general this really slows down gameplay and combat flow.