I agree that the M&P trigger pull is long. What I mean by long is from the point at which you start moving the trigger until it stops in the back of the trigger guard is a long distance. That includes over travel, the distance the trigger travels after releasing the firing mechanism, which is wasted movement. Most of that total distance is taking up slack, also called the first stage of a two stage trigger.
Proper trigger control, where the operator allows the trigger to travel forward only to the point of reset, not all the way to the initial forward starting position, eliminates the first stage of a two stage trigger after the first shot for faster follow up shots with less trigger movement.
First stage trigger movement, not engaging the firing mechanism but requiring conscious pressure to move it a distance to contact the firing mechanism, provides a margin of safety. The longer, and heavier, the first stage, the supposedly safer a trigger pull is under adrenalin pumped conditions.
The same theory of the first stage being a kind of safety is carried to a ridiculous extreme IMO in DA/SA pistols.
Most people firing striker fired pistols don't care too much how long the first stage is, as long as the second stage is manageable. If the second stage is long and/or heavy, gritty, or stacks, or has uneven hitches in it, then many consider improving it. They are looking for a more consistent, manageable trigger to fire the self defense pistol accurately and fast.
I feel the M&P triggers are unnecessarily long in pull for the first stage, and both my Shield and my FS M&P 9 had second stages that begged for improvement. The Apex kits took care of that, including on the FS the Apex FSS kit that shortens the first stage and lightens and smooths the second stage.
While I do not ascribe to light triggers (<4.5#) being an advantage in a combat pistol, I do believe a properly tuned trigger can increase the effectiveness of the gun. There is no advantage to a long first stage pull over a relatively shorter one for a trained individual who practices with the pistol and knows his trigger "feel". The second stage is the more critical one to get "right" for you.
S&W specifies the M&Ps are supposed to have a 6.5# trigger pull from the factory (4.5-5# for the tuned Pro/Core). While I have only pulled a factory trigger on a half dozen standard M&Ps, all have been much heavier than this and were not smooth. The actual second stage length of pull was not bad, but the second stage travel itself has numerous problems.
Factory triggers often are designed to meet lawyers' safety requirements for a lower than average shooter--the person who might get in trouble with a gun because of a lack of familiarity with it. They also are thrown together in the most economical and profitable manner, with their ability to make the pistol fire being the only real final QC required of them. It takes some extra time and effort to make the complicated system actually meet specs, and that costs more than most manufacturers are willing to put into a gun. Since so many consumers buy the pistols and believe the triggers are good, manufacturers have little incentive to do anything different. Better trigger = more $$, either from a higher end model (Pro/Core), the S&W custom shop, or aftermarket parts.
If all you have had is a black and white TV, it is fine; until you get a color one.