The gauges alone are appallingly designed for a start - if your aircraft is not pressurising at 10,000ft the needles are in exactly the opposite sense to where they should be - a quick glance in a busy environment and it looks like everything is fine.
The cabin altitude horn is the SAME SOUND as the configuration alarm. Seriously?? Boeing have had to add warning lights to distinguish between the two because of the original poor design that contributed to the Helios accident.
Lots of people do and should notice that immediately, but guess what - people make mistakes and the easier you make it to do so, the more they'll do it.