The present RPM is rather well suited for installing, but those two items from Debian's DEB would be useful: a) Recommondation A recommendation says a package will almost always need to have another package installed. b) Suggestions A suggestion says a package may sometimes work better if another package is installed. The user can just be informed of this as a FYI. This data is not for the rpm program itself ment, but rather for the use with a installation program (or for inspection of an RPM). This data can also be provided in a text form (Description) but listing packages with version in a "Required" format is more useful. Besides this config advantage it also make DEB<->RPM converting easier.
Without well defined semantics for how these tags are to be used, I will not add. I point out that "almost always" and "sometimes works better" are not exactly well defined. There are many other ways to supply installation hints of this sort without adding to packaging. Simply informing the user is not sufficiently well defined, as rpm is designed to minimize user interaction, and presumes that the user knows what to do with any information presented. Without a clear definition of how the tags are to be used by rpm, making deb -> rpm conversion easier is premature as well.