Comment 18 for bug 1123710

That "apt-get upgrade" behaves this way as it wants to be VERY careful and breaking a recommendation is not a safe operation. Consider situations in which A=1 and B=1 are installed and A recommends B >= 1. Now A=2 enters the archive with B >=2 as recommendation. Upgrading A now would mean we break the recommendation which might very well be an important feature of A which from a user point of view just disappeared after an operation which is considered to be safe and might be even done fully automated! In the case of a new recommends it might be safe, but it might as well be that a package was split or an old feature now needs an addition recommends to work properly …

For "install" and "dist-upgrade" a more visible indication of which recommendations are going down the drain if you apply this solution would indeed be good though (I think aptitude does it) Currently you only get a report about recommends which are not satisfied by this install, not which are going to be broken (on already installed packages). A mode to get the same behavior into "dist-upgrade" and co would be interesting, too – but not as default I guess – as their behavior is defined differently.
(If I recall correctly the implementation in "upgrade" is kinda hacky, so working on it wouldn't hurt either way)