I have not seen anyone note that all major vendors are usually focused on
revenue from new sales and that maintenance income is seen as a bonus. While
new sales are driven by being able to compete with the next vendor, new
features will always be prioritised over stability.
Actually I think in recent history the opposite is true. Anyone remember
the 11.2 and 11.3 [and non 11.1CC] days? Cisco had huge issues
with IOS stability, and its was around about this time that juniper
and a few less successful others appeared. Cisco changed something
and things got significantly better - I'd look at that as revenue
loss prevention :-).