Most likely law enforcement officers would prefer to be able to subdue, immobilize and transport their suspects all in one go. Given the wide variation in body types, and presumably different environments you can find your criminals in (squid aliens are in the water, while bat aliens are flying away), then a portable net projector is a handy, low tech means of doing subduing, capturing and transporting the miscreants in one go.
Anti-UAV net gun with suitable Sci-Fi looks
Edit to add this criminal eye view of a net gun on action
The net mostly has to be strong and flexible enough to wrap around the suspect and withstand attempts to break, cut, bite etc. though it, immobilize the limbs (which is ultimately the idea behind handcuffs), and once the suspect is caught, the ends sealed off and the suspect carried away. If the net comes with built in carrying handles or not is up to the enforcement agency.
I would probably avoid things like sticky nets, or energizing the net, both to make the net usable in all environments, and to prevent the possibility of injury or wrongful death of the suspect when entangled, but local departments might review this on a case by case basis ("OK Officer Blonkins, if you have a positive ID on the suspect, the backdrop is clear and it is a monitor lizard, set the net to stun and fire").
Peace officers might also appreciate the ability to have only one item on their utility belt rather than a plethora of devices.