The question should be more related to the type of water you're on. The type of kayak you're in should then follow the type of water you're on and the type of experience you are looking for...
If you're paddling on water large enough for waves, with currents, with big and/or fast ships/boats, or which is too big to comfortably swim to the shore in clothes, rolling is considered to be a very essential safety measure.
Paddling in a group though is worth even more than rolling. Even if you can roll on calm waters in practice situations, you might not be able to after your involuntary exit. Always remember that there was a reason why you suddenly find yourself outside of a kayak:
- strong winds,
- high waves,
- different waves hitting you from different directions at the same time, created by
- cross winds (even far away),
- obstacles in the water: big buoys can create this, underwater structures,
- ships passing in a distance
- damage to your kayak
- overestimating oneself and/or
Also, if you're on cold water (even if the air temp is comfortable), you may not be able to roll. There is a phenomenon of your breathing stopping suddenly when you get your head into ice-cold water.
In several of these cases being able to roll is not the solution to the problem. Again, being in a group is a much better safety measure. Never paddle alone on open water. And before you go in a group ensure that everyone can reenter the kayak with help from others.
For practicing, get near the beach with a group of people who all can safely and quickly reenter the kayak (as you posted for yourself). All of this group must be able to use buddy techniques to reenter the kayak in groups on calm water. (E.g. one stabilizes while the other enters). Then practice one after the other reentering with waves. First time you do this ensure it's a place with lifeguard on duty and/or boat access.
In addition, learn to read the weather, and weather forecasts.
By the way: If you cannot roll, wear a dry-suit! It helps you stay warm. Never risk hypothermia. Depending on the difference in water temperature and air temperature it's hard to wear clothing to survive 10 mins in cold water while avoiding a heatstroke while paddling normally. I cannot roll my sea-kayak, and usually paddle on a small river (6m width). But I still paddle until the water starts developing ice. I start wearing a drysuit in autumn, when the water gets below 10C because on a rainy day no-one would notice me drifting in the ice cold water. It does not take long to bring your body temperature down to critical levels in 4 C water.
Good luck and lots of fun!