Suspension forks absorb impacts to the front wheel, instead of sending them through the handlebars into your body.

Do you need this? There are pros and cons. On the pro side, this improves stability and control of the bike, and as a benefit of that, improves comfort. In the process some forward motion is lost and turned into heat, but ideally the energy lost is balanced by the improved performance of the rider who is not absorbing these impacts with his body. GCN, for a stunt back in 2017, did the Carrefour de l'Arbre on a road bike, a cyclocross bike, and a cross-country MTB, all high zoot racing bikes with power meters, and the mountain bike had the best time with the least power. But they point out at the end, there's only 50 km of cobbles out of the 250 km of Paris-Roubaix. If you are talking about e-bikes, they are faster and heavy enough that suspension is usually a given. What I observe in this forum in practice, is that people who have long commutes every day eventually settle on some flavor of road bike, while short-haulers like myself use a much wider variety of bikes, that are more likely to have suspension forks.

You may wish to have a suspension fork on your bike because it is in dual service as your commuter bike and your mountain bike. Suspension forks very often have a lockout, or you can crank down the low speed compression damping, and the bike behaves much as if it would with a rigid fork. This may not be all that important. I leave my own suspension fork unlocked and find it does not move much at cruise, seated level pedaling. Since it doesn't bother me, I leave it open. Otherwise I tend to forget to open it back up for the trail.

As for weight, yes it adds weight. It might not be as much as you think. As with all bike stuff it's definitely a price for lightness. The heaviest suspension forks weigh nearly six pounds but the most premium are less than three, and a rigid chromoly fork of the same size still weighs nearly three pounds.

Enve carbon road fork 370 grams
Salsa Waxwing fork (carbon gravel bike) 520 g
Surly Cross Check fork 1050 g
Salsa firestarter fork (heavy duty chromoly) 1200 g
RS SID SL (premium XC fork): 1326 g
RS Reba (nice XC fork): 1586-1662
RS Judy Gold (inexpensive but ok): 2009 g
RS Judy TK (steel stanchions, coil spring) 2545 g
Suntour NEX (coil spring, hydraulic lockout): 2550 g

There's a case to be made for bigger tires. They do improve the ride comfort. Still, this acts like an air mattress compared to a real mattress. There's damping but it's not enough. There seems to be a reasonable limit of about 2 inches for balloon tires, which gives maybe another half an inch of deflection vs a regular commuter tire, while a suspension fork can make a lot more. There are a few fat tires built like roadie tires that can be run very soft. Although Rene Herse tires performed poorly at the Bicycle Rolling Resistance site, adherents argue that they result in an overall more efficient ride - much like the argument for the fork, you may notice.

Someone might chime in to say a suspension fork is bad because it has elastomers that might be worn out. This was something tried out in the 1990's. The spring and damping were both provided by dense foam rubber - multicellular urethane, or MCU. By the early 2000's they were all gone from the market, and rightly so. Not only did they wear out quickly, they also tended to turn to goo in the presence of any lubricants. You are only likely to find one of these on a 1990's mountain bike and if you do, feel free to run the other way. Forks made today have rubber bump stops, but not anything like this.

Suspension forks use oil and grease and seals, and so they do ask for occasional maintenance. At the level we are discussing, they are not complicated, using mostly mechanic tools. Rebuild kits and spare parts are available, and instructions for the service can be found in PDF or video form.