Hard problem, I've seen that as well in the past. Analyze deeply what it is they're trying to improve in the whole. Then ask them hard questions, trying to get to the deeper problems before jumping to solutions.
- why you'd need Project Management meetings
- how the Scrum Meetings are not supporting that
- How creating a ghantt chart differs from creating a plan during the sprint planning meeting.
- Are their planning meetings currently effective?
- Who it would be helpful to if they did hour tracking?
- etc.
You might find that the developers do not want to be accountable for the plan and the product and prefer to do as told, which is hard to break through. In that case, read into the dysfunctions of a team, before teams can be held accountable, they need trust, conflict, commitment before accountability. This is a great book (there are a lot of presentation available on this subject as well on sites like slideshare.
The final thought I have is that there is a (perceived) pressure to deliver. That the backlog only gets larger as they deliver new stuff and that the team needs motivation that they're doing their best and are delivering the right things. It can be very demotivational (and kill commitment) if you're constantly being told you need to be more productive, deliver more, faster and cheaper. It kills the drive to improve and it generally takes away the time that's needed to put these improvements in place.
Slow down to go faster