In general, front hub is only for bikes that cannot have a rear hub for some reason. Mostly this reason is things like the only brakes are a coaster brake, belt drives, shaft drives, internal gear rear hubs, and trikes that can only use a front hub. But in some cases, weight distribution is also a valid reason. If you are going to carry a 40 pound lead battery in back, you may want to move the hub weight up front. This arrangement was pretty standard when lead was the typical battery.
But now, with a 1000 watt hour lithium battery only weighing 16 pounds or so, The only reason you'd carry the motor up front would be if you plan to overload the back with cargo. Enough to wreck a weaker motor wheel. This cargo could of course be your own body.
But for most people, under 250 pounds body weight, the modern lithium battery can be carried on a rear rack, with a rear motor, and not affect handling aversely enough to care about when street riding.
For dirt trail riding, a rear hub is nearly mandatory, and then you attack the problem of moving the battery forward if it weighs more than 10 pounds.
So in short, it depends. Depends on the bike, depends on the rider, depends on the ride, depends on the weight of the battery involved,,,, and on and on.
But one thing for sure, Nothing super wrong with front drive, a simple coaster brake beach cruiser with a front hub can be a marvelous ride! You might seriously consider buying a cruiser for your next bike, and change your current bike to the rear hub. But after 10,000 commuter miles with front hub, I don't miss it any. I'm slightly more confident with any riding on dirt or gravel with the rear hubs on my street bikes, and don't wear out the motor wheel tire abnormally fast anymore. I could have had less tire wear, but I usually just gave full throttle and would spin the tire for a foot or so every start.
As for your torque arms, yes it's important shit. But your current ride is fine, your TA install is perfect. You can stop fetting about that.