Mouser, i think we are still talking about huge systems (user data of a credit card system) and believe me, your arguments are wrong on this scale. These systems are planned for project durations of several, often ten years. Designing a system that grows up ten years will definitely not work. And not because of the costs of disk storage. The costs for hardware are negligible in these projects. Lets say you need a good server for 50.000$. This is nothing compared to the other costs. The main point why this don't work is time. Because your database is constantly growing, its performance will constantly slow down. The query which took 0.1 ms in the beginning takes now 1 ms. The mouse click in the client which took 1 sec in the beginning takes now 30 sec. At this point the big manager will call you and will present you the following calculation: In the beginning 500 persons did a particular amount of work. 500 persons need 17.5 Mio $ salary the year. Now they can finish only half of the work because the application slows down day for day. So the same amount of work costs now 35 Mio $! I assure you, this manager won't be grateful that you offered him the possibility to resurrect the data of a user which died 5 years ago.
Others problems follow, e.g. the time for making backups grows from 5 minutes to 2 hours. This can be problematic when the company wants to make cold database backups (the database must be shutdown), because the down time is lost time....

Please don't misunderstand me. I'm on your side regarding 99% of the applications in this world. It's great to have undo and redo, and it's ok to disable a *reasonable* amount of data, but you can't make this a global programming rule.

If i couldn't convince you, i suggest one experiment: Let's simulate the "Disabling over Deleting". We don't remove files and directories anymore, but move them to recycle bin for one year and discuss the results in Oct 2008.

Finally i disabled showing the signatures of other users. The last straw was a signature with an animated image. In my opinion a signature should be an addon to a posting but never should detach the attraction from the content to the signature. The content of a posting is the important part and the signature should be small and unintrusive. It's a pity to disable the signatures because i liked many of them, especially when they contain links to interesting sites, but the current signature rules offer too much room for "abuse".