Leather will save you some road rash. Its not the warmest but it cuts the wind pretty good.
The main thing is we should try to avoid direct contact with the road anyway. Just in case I would wear riding gear even if you live in a warmer part of the country. I want a couple sets of riding gear for the hot and one for the cold.
I have 2 leather jackets, sometimes I wear them and they work pretty well, but they honestly don't do anything that my textile/ armored jackets don't do as well or better and cheaper.
If you like the leather look it's a good choice but if not then why buy one, cruisers ride just as well without leather
The simple answer is YES. Everyone should own a leather jacket. I own several but don't wear them much anymore when riding the bike. The leather is too heavy and has other issues. I wear mesh fabric jackets with armor in the summer for coolness and rain rated fabric jackets with armor in the cooler temps. I also wear full coverage helmet all the time, boots all the time, armored gloves all the time, and armored pants only sometime. Seems to be a progression. The more years I go the more armor I wear. While I never was a flip flop wearing rider I was a helmetless or pretend helmet and tee shirt wearing rider for a good number of years.
Fashion-wise, sure -- everyone should own a leather jacket.
Now, they are certainly nice for riding, too, but be aware that not all leather jackets are created equal. A jacket designed for riding will have certain features - thick leather, reinforcement in appropriate areas, zippered pockets, snug closures at wrists and neck, etc. While most leather jackets will give you better protection than, say, a long-sleeved shirt or even a denim jacket, they are not as protective as a genuine riding jacket. The features of a genuine leather riding jacket mean they are expensive, so if you want enhanced protection and money is a consideration a quality textile armored jacket will do more for you than a "style-oriented" leather one.
I used to ride in a black leather jacket. It was heavy and armored and felt very protective. However, when it rained for more than a few minutes it would absorb water, making it cold and excessively heavy. If it got completely soaked, the dye would leech out, turning my body and arms a light purplish color for a couple of days.
I've had both leather and textile and prefer leather unless its really hot, in which case I wear a mesh textile jacket and pants. One advantage of leather is that it doesn't need to be washed, ever. Any grundge on it can be wiped or scrubbed off whereas bugs and dirt get embedded in the fabric of a textile jacket. True, leather is not waterproof, and I have to wear a rain jacket over it, but unless you get an expensive Gortex jacket, most "waterproof" textiles use a water proof liner under the outer fabric, which still gets soaked and heavy. To me, an old, well used leather jacket gets to fit like a favorite pair of shoes and just feels right.
I just picked up a leather coast but it is more of a track/sport coat then a cruiser leather. It has metal shoulder pads, added back armor (upgraded), and full elbow/arm protection. I really like my textile for all around but I think the leather will be more protective for a day on the "tail of the dragon" or other more technical rides. Definitely more protective but a lot of them are as good as the armor