First off, let me say I'm not a fan of striker fired guns. But............ for what they are designed to do, which is be an effective COMBAT pistol (meaning be able to consistently hit a man sized target at 25 yards), they fill their role very well. I just don't shoot them as well as other guns, including DA revolvers. In my world, a 70% shooter under time in training becomes a 20% shooter in a real gunfight, so I want EVERY advantage to raise my percentages that I can get. That's why I don't carry a striker fired gun.
IME, the safeties on striker fired guns are more of a hindrance than a help to me. The examples that I have personally messed with I found to have small operating surfaces, making the likelihood of missing the disengage when it's really needed a REAL problem. I've typically found the trigger pull on a striker fired gun to be long enough and heavy enough to not "need" an external safety. And with that statement, I'm sure someone will come along and try to roast me alive about the word "need".
As a 20+ year police officer, I work for agency that allows us to carry what we want, within policy guidelines. I carry a 4" lightweight 1911 on, and off duty for years. Of course, it has an external safety, and I've argued against manual safeties on some guns, but I see the purpose on others. As others have said, if you TRAIN to keep your booger hook off the bang switch, there "should" be no need for a safety. As a decade long firearms instructor, I own and shoot the 2 makes of guns that I see the most of in the striker fired category (Glock and Springfield XD). I have never once even recalled thinking, "boy this thing sure needs a safety".
Folks in my profession have done it for a hundred years with DA/SA revolvers without a notable number of mishaps, as long as one didn't wander around with the gun cocked. There's a huge difference between a LONG 5-6 lb pull and a short 3.5 to 4.
Anyway, that's a long winded way of saying that IMHO, striker fired pistols don't "need" a manual safety, as long as the "end user" is training as they should. If they aren't, a safety likely won't help anyway.