We added report page tooltips back in March to support this. You can learn more my blog post here: https://powerbi.microsoft.com/en-us/blog/power-bi-desktop-march-2018-feature-summary/
It’s currently in preview, but we have plans to add support for table and matrix, and shortly after make the feature generally available. At that point, I’ll close this idea.
Quick update, as there are many of you patiently waiting for an update. We’ve started to implement this feature in the service. Look forward to rolling this out to you soon!
This is a great suggestion, and something we’ve discussed in the team. If more people think it’s important, please cast a vote and help it get prioritized!
1,151 votesAshley commented
Common problem and very important. Please add this.