If it's just in your name then when you pop off it will be frozen and she'll have to go through all the hassle of transferring it over to her name which all takes time, and meanwhile she won't be able to touch it, even if it's clearly left to her in the will. The bank cannot give her access until their own legal bods clear it.
It's much easier just to change it to a joint account now.
Legally there's no need, but practically there is, particularly if most of your cash is tied up in your account - the last thing she will need after you go is to be skint for a few weeks.