I actually don’t mind the absence of text with the invitation. Multiple reasons:

• I don’t know when someone actually needs some help and I might be in a position to offer that help.
• You can send a connection request on linkedin from many segments — for example the suggested profiles block when you add someone else. If you click on “connect”, linkedin auto-sends the invitation (or at least it used to; haven’t actually sent out an invitation in months)

But you are right. People should ideally take care of that as well.