This is certainly an option with smart bulbs. Or with in wall relays. People also use Wi-Fi mobile phones for this.
As you mentioned, it’s a popular use for SmartTiles.
However, there are a couple of issues to consider.
The wall mount tablet gives you no more options than holding the mobile in hand does. It’s just more convenient positioning. That means:
One) it cannot control a nonnetworked fitting. The device you are controlling from the tablet must have its own network identity. Again, that could be a smart bulb or it could be an in wall relay or a pocket socket. So the wallmount tablet is an additional device cost to whatever else has been done to provide home automation.
Two) it will only work when a connection to the smartthings cloud is present. There is no local operation possible if the Internet is down or if the Internet is up but the SmartThings account is not available. That won’t matter to some people, but it will matter quite a bit to others.
- The tablets almost always require that the person have pretty good reading skills. For this reason, they are not always suitable for small children. They may also be problematic for guests who require reading glasses and don’t expect to be wearing them when just walking around the house. The following applies only to a very small subset of users, but since I happened to be one of them, I will also mention that the tablets cannot be used by an assistance dog.
So many people do use the wallmount tablets and like them, but they are generally used as an additional means of control, rather than the primary.
At my own house we use many different parallel means of control. We do have one wallmount tablet on each side of the house, but we also have a physical switch for each light as well as voice control. So just comes down to each person’s preferences, use cases, and budget. 
There is a thread in the forum where people have shared projects for Wallmount tablets and phones for use with SmartTiles. Although obviously some of the equipment is only available in the US, It might provide some additional ideas and inspiration.