I think you did a good job of hitting the nail on the head with regards to why you’d migrate to Meraki. The Dashboard is the real key to the Meraki solution.
It will provide you that single point to monitor and manage your network across all your devices - without having to connect to individual devices and remember (sometime obscure) command lines. It also provides you and great, and still growing, API if you don’t want to get completely away from the command line or scripting for automation or those time consuming iterative tasks.
You don’t mention the size of your network, but the place I also find Meraki excels is across multiple sites when you’re trying to manage or maintain the same (or similar) configurations on multiple wired or wireless networks. It can also be great on a large single site too, for example where you want to configure multiple ports on multiple switches in one go.
From a cost point there is always a cost of change, but the key here is to consider the reduced operational overhead from the Dashboard, as well as getting brand new hardware. You should also make sure you’re working closely with your Meraki AM or partner to ensure you’re getting right-sized hardware, and the right pricing for your migration (they’d love to see you on a full-stack Meraki solution).