What makes Asterisk a more technologically advanced piece of software over the software that runs various proprietary systems?
For example, how does the technology of an Asterisk IP PBX compare with that of a large Nortel, Avaya, or Panasonic system? Don't think Switchvox or Trixbox.... think pure OS Asterisk software built using best of breed hardware.
I'd like to say Open Source is almost the clear choice, and it may be the right one in some cases. However, the fact of the matter is that Asterisk is so extensible that it some times hurts the product. There is a common risk factor. End users, they are your greatest asset and threat at the same time. Distros like TrixBox have the right idea, build a distribution and implement "Service Modules" to handle the configuration of tasks.
Now this answers the cry of all the "mom and pop's" out there, lets address "Big Boy Corporation." Larger corporations need a security blanket and if you can't offer that then your out the door. Most open source products do not offer that. However if you are "Super VoIP Man", the one man consulting operation, it presents a unique niche market. Yes Asterisk is Bad @$$ and can do many of the things that XYZ Big Box vendors offer and more. But there are points where it takes extreme amounts of time to compete with 'out-of-box' features that XYZ have.
Some of these Key features break down to Survivability and Redundancy. Many businesses have put together exceptional plans that can recover failed systems or distribute load across a multitude of physical servers. But if "Super VoIP Man" gets hit by a bus tomorrow - how long do you think that system will survive without you? Defiantly not past its next major upgrade. Big Boy Corp.'s around the world know this and in an instant you and your service become a risk.
Lets examine one other scenario, Big Boy Corp.'s IP enabled contact center. Transacting 20k worth of calls a day IVR's w/ speech recco, Advanced ADC call treatment and distribution, recording and analytics, geographically disperse locations. I can guarantee that there is not a single open source solution that could deliver a working, STABLE (keyword, stable), highly available solution like XYZ Big Box can. Why you ask? Well that's easy, MONEY. Everyone out there is driven harder by the influence of money to make things faster, better, and easier to use. Big problem in the industry, throw some money at it, guarantee it will get fixed.
There is always going to be a niche market where Open Source solutions (like Asterisk) fit, and that market is always changing. But when it comes to playing the game with the big boys the guys with the deep pockets will win, basic economics.
Now for every Asterisk VoIP wizard out there (I wish there were more) I have one recommendation .... focus on integration solutions. Many save thousands (for example in Cisco Device Licensing) utilizing Cisco Communication Managers and a SIP trunk to an Asterisk server catering to Wifi SIP endpoints. For home you can use Askerisk (on say a Linksys router) to power all your wired and wireless SIP endpoints.
In conclusion Asterisk is a great product and can (be configured to) do a lot of things. But it is simply not Big Boy Enterprise ready - and may never be for that matter. As long as it is a open source solution.