> In november 2008 bitcoin was a much younger ecosystem,

Or very old, indeed, if you are using unsigned arithmetic. [...]
:-) I meant 2012, of course, but loved your wit 
 
> and the halving happened during a quite stable positive price trend

Hardly,

http://bitcoincharts.com/charts/mtgoxUSD#rg60zczsg2012-10-01zeg2012-12-01ztgSzm1g10zm2g25zv

indeed!
http://bitcoincharts.com/charts/mtgoxUSD#rg60zczsg2012-08-01zeg2013-02-01ztgSzm1g10zm2g25zv
 
There is a lot more complexity to the system than the subsidy schedule.
who said the contrary?

This thread is, in my opinion, a waste of time.
it might be, I have some free time right now...

many people have performed planning around the current
behaviour. The current behaviour has also not shown itself to be
problematic (and we've actually experienced its largest effect already
without incident), and there are arguable benefits like encouraging
investment in mining infrastructure.

I would love a proper rebuttal of a basic economic argument. If increased competition will push mining revenues below 200% of operational costs, then the halving will suddenly switch off many non profitable mining resources. As of now the cost per block is probably already about 100USD, probably in the 50-150USD.
Dismissed mining resources might even become cheaply available for malevolent agents considering a 51% attack. Moreover the timing would be perfect for the burst of any existing cloud hashing Ponzi scheme.
From a strict economic point of view allowing the halving jump is looking for trouble. To each his own.