I've got this same issue. Our daily reports (HTML) increased from ~500kb to ~2MB immediately following the same upgrade as you've listed.
We have the same issue. We like to keep a history of all our daily reports to look at the changing trends. This is going to increase the storage requirements for our monitoring email accounts. Plus we receive these reports on our mobile devices so this increased size is also chewing up our mobile data.
Ideally, we would like to choose between Simple Text, HTML, PDF, Excel etc for our emailed reports.