A Rav told me that he advises hasanim to break the glass with the heel to avoid a trauma.
We have numerous cases in Gemorah when a practice was called off due to freak cases that happened.
For example, a cohen breaking a leg when running to get avodah. Apparently, they did not wait for the second case.
Maybe there were close calls before with cohanim pushing each other? For many dangerous events, close calls are a good predictor. For example, number of sudden stops when driving is a good predictor of someone who might end in an accident. So, think of close calls and correct your middos accordingly.