Currently, the tabs for "Recent Folders" and "Recent Files" on the "Start Page" show very large folder icons. I think it is safe to assume that if the user chooses a smaller size in Browse mode, he would be fine with more items displayed at the expense of smaller click targets on the Start Page too. Note that this does not yet mean there should be a zoom slider on the Start Page. If there are changes in that direction, it would be better to rethink the whole relation between Start Page and Browse mode a bit, as this is a bit weird right now (Esc not going back, no sidebar, no breadcrumb bar etc.). See also Bug 202417 and Bug 303631 in that regard.
On second thoughts: Maybe the original intention was to give more space to the thumbnail overlays on the folders, so you could better judge what a folder will contain? Note that's not so much an issue once you entered some folder. Still, the large size / few entries are a bit annoying. Maybe another structure would fit better, i.e. a vertical list, where each row would start with the folder icon, with some preview images next to it. Next recent folder on next row.
I think your vertical layout would work best, moving this to wishlist.