Not sure who you are asking this, in the "Show off Your Dashboards!" thread, but I'll answer it. Yes. Are they perfect, no. But what you get covers what most people need to control their devices on an automation platform.
Assuming this is in reference to the Device name? You can change that, it's in the Device Details on the hub.
This has been asked for many times and is on the feature request list but our current rationale for not allowing this, is it could cause confusion since the name and label already allow for device display name customization. This may change down the road, but at the current moment, you can change the device label and that shows up in dashboard.
First I've heard of this request to have a slider with preset levels. I'll certainly add it to the list. As for limiting the fan template, unfortunately the current drivers do not have a supportedFanModes to query so those are the values the capability allows so its up to the driver...
This is simply not possible with the current architecture.
You are not required to use dashboard, there are several very good alternatives and no single solution will satisfy every single person's needs.
Of course, anyone is free to build a better dashboard solution as well. It's not an easy task (trust me, I've written several) but we provide Maker API for that reason or you can write your own groovy endpoints and serve up HTML where you see fit.
Hubitat Dashboard is an ever evolving app and will continue to improve and add features requested by our customers.