There are many ways to build a list, and tactically we want to have as many options as possible since we can never be sure of the exact mission we will play, or the exact army we may face across the table.
In my own list building templates and theories, I always try to select models that can deepstrike, outflank, or infiltrate as they allow different entry points onto the game table, over the usual this-is-my-side-this-is-your-side setup.
Many models in all the codexes have these USR’s in their listing so taking them for other reasons works out well also.
The think to keep in mind is that just because a unit can deepstrike, infiltrate, or outflank means it doesn’t have to do that.
Look for models with USR’s built in, which can work as just another tool in your toolkit- something to take advantage of tactically IF it presents itself based on the mission and the moment, and if not, you still have the other base attributes of the model.