Yep, sideplates typically suffer damage to the legs (or prongs) that fit around the left end of the sear pin because of inattentive armorers (or untrained hobbyists).
While I certainly wouldn't recommend detailed frame disassembly be done by someone that hadn't been trained to do so, the method I use to remove the sideplate is a simple one.
Once the grips have been remove from the frame, I hold the frame in my left hand (I'm right-handed), left side facing upward, with my left thumb gently holding the front extension of the side plate (no pressure, just keeping it stationary and given me an "index" of its position) ... and then I use a plastic mallet to smartly whack the
left end of the sear pin, snapping the sear pin out (to the right) from between the sideplate's legs.
This prevents any outward (leftward) pressure or leverage being exerted on the sideplate's legs, like if someone's trying to lever or lift the legs off the frame. They're remain flat against the frame using this method (since they can't try to follow the disappearing head of the sear pin as it snaps out from between them moving to the right).
Once one the legs has been tweaked or bent, it's best to simply replace it. It's usually the rear leg that gets tweaked or bent. The reason is due to unwanted pressure exerted against the bottom/front edge of the sideplate during installation of the factory grip, simple leverage resulting in the sideplate's upward shift putting pressure against the rear leg at the bottom of the sideplate (which is being kept from moving forward by the sear pin ... so it bends). Improperly trying to pry, lever or otherwise lift the sideplate legs to the left can create the opportunity for one of them to acquire a bend, too.
Sometimes it might be possible to straighten a tweaked sideplate leg, but more often than not the leg breaks off (or is now weakened).
This isn't a design weakness. It's an armorer or owner ("kitchen table gunsmith") caused "problem". Kind of like how stripping the threads on a screw isn't a "design" problem or weakness, but a problem caused by the "loose nut" trying to operate the tool to overtighten the screw.
Now, I use a different method than originally taught to me to install the sear pin and anchor the sideplate. We were first shown to install the sear pin from the right side (with the left "headed" end of the sear pin oriented on the left, so its recessed groove can capture the sideplate's legs). Then, we were shown to hold the sideplate with our thumbs and use a cup-end pin punch to push against the right end of the sear pin. The only thing keeping the sideplate legs "flat" was the pad of our thumb, though, and shoving the left end of the sear pin against our thumbs, while it was pushed between and through the sideplate legs. Not much in the way of a firm surface against the sideplate legs ... and the pin being pushed into your thumb could be less-than-pleasant. (Especially if the pin punch slips, which can leave a mark on both the frame and you.
)
I forget who showed me a better way, but it involves placing the frame on a hard work surface (not your wife's kitchen table!), on its right side, with the sideplate (left side) facing upward.
The side plate is slightly up and off the frame, sitting on top of the sear pin's head (with the sear pin being held flush on the right side by the hard work surface).
A maple armorer's wedge (wooden handle of a cleaning brush, or any other non-marring flat edged tool) is positioned against the left side of the legs, just "above" the sear pin, equally against both legs ... and then a gentle, but briskly firm, push against the legs causes them to quickly snap outward around the head of the sear pin, and slip into the pin's groove. The flat edge of the wedge (if held flat against both legs) helps minimize the potential for the legs to be bent, becoming uneven in relation to each other.
Here's a couple of pictures of what I mean ...
In this picture the sideplate is "prepped", ready for the pin to be driven through the legs, and the sideplate to be pushed against the frame for installation. (Ignore the patch, it's only covering one of the serial numbers.
) The flat of the wedge is positioned close to the head of the pin to minimize the chance of either of the legs being bent upward/outward.
Gentle, brisk & firm pressure against the wedge has caused the legs to quickly snap out & around the head of the sear pin, where they're now resting within the recessed groove on the sear pin. This has also pushed the sideplate flat against the frame.
This is what it should look like afterward. The sear pin has been captured by the legs, and both legs are flat against the frame. Anti-climactic.
Some sear pins, showing the groove intended to hold the sideplate's legs.
Outside of a frame, sideplate legs/prongs fully snapped around recessed head of sear pin, showing full engagement in recessed groove around head of pin.
I also had it ready to go to the range to be fired for the first time as well... 
The sear spring retainer pin would still stay in the pistol because of the grips stopping it from working out either way, so it would still function.
