I used to be a fanatic about using filters on every lens. It became my standard practice to buy a new lens, then not even take it out of the box until I had the proper UV for the front. And not just any filter either, they needed to be B&W or Leica or Schneider or something really great and really expensive. After all, I wanted the best quality in everything, so the cost of a good filter was just part of the cost of entry.
I shot for years this way. I didn't know any better. I used to come home after a hard night of shooting, download my night's take, and examine what I got as keepers. I learned to live with the light smears, the "rays" around strong light sources, and all the rest of the aberrations caused by stray light reflections. Some interesting, most degrading the particular image to the point were it was unusable in my opinion.
Talking with some other professional photographers, I began to understand what the problem was, and what was causing it. It was obvious, and quite clear in my images, though I didn't have the background at the time to understand what was causing the problem. I was seeing correctly, and compensating by staying away from shooting direct light sources right into my lens. I was crippling my technique because of flair, and cursed the designers of the lenses I was using for causing this problem.
The night a good friend suggested I remove the filter, and shoot a series without it changed my life, and ended my use of filters for good until the M8 came along. All the proof I ever needed, that camera provided. My conclusion, and I freely admit it is a personal choice, was that filters do a fine job of keeping dirt off of my front element, but at a cost of greatly increased flair problems.
Shooting at the beach as your regular set, maybe you do want to use a filter. Your likely not shooting there at night anyway, and most likely you would have the sun at your back most of the time. Blowing sand or dust, your probably better off gear wise if you just pack it up and go home. Blowing sand and dust can do far worse than getting on the front of your lens. They can both penetrate into the innards of your body if it isn't weather sealed, where they can really cause havoc. Or buy a suitable beach camera, and use that. My wife has a little Canon that is great at the beach, and even capable of shooting underwater down to about ten feet.
For myself though, the difference in my keeper rate shooting without a filter goes up especially shooting at night. I do this for my living, so having as high a keeper rate as possible means money in my pocket. Sure, it's possible one of these days I could get a scratch on a front element. Probably much more likely cleaning my lenses, if I am not careful. Though all the years of shooting with filters, I never had to replace a single one due to damage. Nor have I had to repair a single lens shooting without one in the many years since. Given the high cost of a good filter, I am probably money ahead in the bank when and if I ever need a lens repair. And I guarantee you I am money ahead shooting professionally from having those extra images for my clients I could not have produced using filters.
The rules are different for working professionals. We have to get the shots. We have no excuses when we don't, it's our job. Cameras may be our passion in addition, but fundamentally we must work in such a way that our gear earns us our money - or we don't eat. We're only as good as our last job, and only successful if we meet our clients needs. If meeting that bar means occasionally some of our gear is at risk for damage, that is just a part of the cost of doing business for us.
I don't want to come off here as playing the "P" card either, in dismissing the other side's arguments. There are some very valid uses for filters. For me, it all comes down to doing the math. Each of us is different, both in technique and the subjects we shoot. Speaking only for myself, it is a 3% to 5% difference, or somewhere in that range. Out of 100 frames, if I use a front filter I can count on having three to five of those frames on a night time shoot being unusable for my client. Personally, I need those good frames, as I have no idea in advance if they will be important or not to the story I am shooting. What I do know is the frames I can't use I don't get paid for, and the important ones I can't replace are holes in the story I can not fill.
In the end, we can all debate this subject until the cows come home to no general conclusion that is right for everybody. Photography is an art, and as such is subject to interpretation with no hard and fast rules that work for everybody. I would suggest though, if you have problems with random light patterns especially in your strong sun shots or when your shooting at night, you may want to conduct a test for yourself. Try shooting a couple hundred frames with your filter, then take it off for a couple of hundred frames - in the same lighting - and see what you get. You many just find your answer to better personal photography. If you aren't having a problem, you don't need to bother. It's not a problem for the type of work your doing.
One thing I will agree with, if you decide to use front filters, use the good ones. Multi-coated filters have those coatings to help limit these problems. Which, I guess, is all the proof anyone should need that problems do exist using filters!