A big part of it is that once you get to a system for many tens, hundreds or more people, the basic requirements are so big that there are no real choices beyond the main one or two competitors, and one will be ahead for one reason or another.<p>Users have no voice, but that's only part of the problem - the time it would take to evaluate New Competitor C just to cover all the unspoken requirements is prohibitive. You can be pretty confident that <i>because they claim</i> nice sounding features and a simple interface, that's proof that they haven't been around to gain enough of the unspoken requirements - if they had, they wouldn't have nice sounding features and a simple interface anymore. Bit of a catch 22, really.<p>Unspoken requirements in the Windows world are things like "... and has a web interface", "... works on a terminal server", "reports integrate into central management program X", "has an Outlook plugin", "tolerable support for user permissions", "incomprehensible massive logfile", and so on. Either things that a program which incorporates all of them will be cumbersomly big by necessity, and/or an established competitor for several years with a few versions under its belt.