rj wrote:Could you expound on that!

I delete articles here and there, what is the adverse affect of that?
Gladly! There's no adverse affect whatsoever.
Oh, you want more detail?
What I'm really saying is that Serendipity is designed for speed, simplicity, and security. Why? Because we (by which I mean Garvin and his cohorts; I wasn't here at that time) envisioned it as the original blogs were -- online diaries. Nothing more or less, no fancy stuff required, just a listing of past events and the observations that go with them. It ships with only the stuff required to do that job enabled; if you want to get fancy, you have to enable something extra, maybe even install a plugin.
In a regular diary, you don't rip out the pages. Usually. I suppose, if you had a really bad breakup, or if you said something stupid and needed to erase 18.5 minutes (sorry, American politics reference)... but usually, you keep everything around for later examination. So Serendipity has a delete function, and it works perfectly, but we expected you'd use it only rarely.
Then there's the revolution. People want Serendipity to work for multiple users, be a CMS system, connect to their ShoutCast servers, track their schedules, provide a gallery for their pictures, host forums, and do their homework. Luckily, the plugin system is so powerful and flexible that it's easy to write plugins for all those things. (Well, maybe not the homework.) So we do.
Suddenly Serendipity can do lots of stuff besides an online diary, and it's speedy, simple, and secure besides. The world recognizes its inherent superiority over all other web applications, flocks to it, and we all become rich and move to big mansions. (Yeah, right.)
But... we never thought we'd need an auto-delete function. It all started as an online diary. It still ships as an online diary. You CAN make it do a lot more, but it's never needed an auto-delete, because you generally don't want to delete entries from your diary, never mind AUTO-deleting them.
It's not too hard, though. The manual solution you mentioned would work just perfectly, and it's not a lot of work. And the plugin system is
so phenomenally powerful that a plugin to do the auto-delete could be easily created. Almost has, in fact, and making modifications would be a nice introduction for a future Serendipity All-Star Developer.
So, no adverse affect from deletion. Just that automatic deletion isn't something that was considered, due to the original intended usage of Serendipity.