When I bought my Shield 45, it was the only one available at my LGS, and it had the safety. My previous carry gun, a Shield 9, didn't have a safety. Based on my prior experience with M&P safeties, I wasn't too thrilled...but this one seemed much different in handling it in the store, so I bought it. Now, I'm glad I did. It is unobtrusive, clicks on or off positively, and doesn't offer any real potential to engage or disengage unintentionally. It gives me the option to engage it if I want, or leave it off. I've come to prefer using it, and I do practice disengaging it.
IMO, either leave it off or use it, and practice disengaging it (as you have been doing.) Gluing it down is really bad advice. If you truly want it gone, have a gun smith remove it (or do it yourself if you have the ability) or sell it and buy one without it.