I think this topic has 2 sides at least.
First, clients' side. I'm sure any client who is paying for the service want to have a control panel with friendly interface and have opportunity to manage it easily. For some clients it might take a while to master new control panel.
Second. Providers' side. It is a dilemma, because from one hand they need to shorten their spending on licenses (to make hosting services price-attractive) and from the other hand have their clients mastered new control panel easily to avoid creating lots of support requests like :
- how do I add email?
- how do I add domain?
and the others.