Hot toys spent months engineering and designing the light saber arms and the way they work. They couldn't find a better way that didn't add substantial cost. Swap out parts are a huge part of hot toys so there's no reason they would not use it. The only other option they found and tried was a swap out hand section that hooks to internal wires. But it was just to prone to breaking. Exposed or swap out wires are just something that has proven to much of a failure rate. People hook it up wrong or break it and then ask for refunds ect. The way it is now is the best option for the price. If you want a figure that costs significantly more they can do pretty much anything. But it's not just about can they do it.
And I can't see any way anyone would be ok with having a wire you could see. When people flip out about the gap between an upper lip and nose, or the cape material or the hundreds of other little things you see brought up as issues. It's easy to say there's a better way.
There can be many reasons why they move forward with a design choice and it's not always the best. Regardless, I'm not ranting on Hot Toys mindlessly, I'm merely bringing up that their current design can be improved and opening up the forum to ideas. One can't say they couldn't find a better way... I mean, look at Thanos's Throne. That was just a bad decision to put the switches inside the battery compartment. Making Mark 42's and 43's helmets switches on the tops of the head instead of the face, also not the right decision.
With Whiplash, we are modding him with these ELs that could have been used instead of LEDs in the first place, and still been battery powered.
Don't get me wrong, I still think the arm swap was a clever solution for the light sabers, I was impressed when I first saw it. But I'm open to seeing what other ways they can improve, such as induction. After receiving my Kylo, the arm swapping was not nearly as easy as I had hoped. I'm afraid of ruining the fabric if I swap it too much, and turning on the switch isn't the easiest through the clothes. Because of that, I would be okay with a wire of some sort...
Budget Stark has a video of the Soap Reactor which makes HTs wired. Yes, the back can be a mess, but again, for photographers, this is absolutely fine because I can compose the shot properly and I don't have to worry about wearing down the batteries or turning on each individual switch between breaks.
When a figure is ready to go back in the cage, you take off all the wires much like I would take out the batteries, wouldn't want to risk leakage.
Again, it's a subjective trade-off, while you can't imagine anyone that would be fine with wires, SOAP Studios is betting their business on it.
FYI to anyone interested in the SOAP Reactor, get the 10v power adapter (sold separately) the same time you get the full kit, otherwise you are paying a ridiculous shipping fee later. SOAP Studios is the only one that makes a compatible 10v adapter. Otherwise you can use a universal one, but none are exactly 10v. I am running mine at 7.5 volts.