Looks like you have plenty of replies to sort through here...and it does seem that you have some overly sensitive musicians, but my opinion is that emails to your worship team should be used only for communicating dates/times, checking scheduling availability or giving praise to them. I suppose you could send out a prayer request if it is an appropriate one.
I'm curious if ALL your team members were offended, or just one or two? If it was really one or two people causing the distraction, then they probably know who they are and they may feel like they were "called out" in front of everyone via the group email. Or, depending on the relationships that already exist between team members, one member could be "taking up another's offense" and as nearly ALWAYS happens in that case, grossly magnifying it.
Trust is the basis for instruction/coaching/admonition and trust takes time. Plus, you WILL run into people who are simply too immature to be teachable. "A fool despises instruction..." Prov. something... and unfortunately there are foolish people out there.