When a software is built for a life-support system it is definitely a life-n-death situation if anything goes wrong. You might say that it does not have an immediate impact during development but in the long run a life-support machine may abruptly shutdown due to wrong security implementation or stop responding due to poor performance considerations in the software architecture. The project management would definitely need to do proper costing for proper designing of the software by employing the skills of a software architect. No role is dispensable when one commits to deliver quality sofrware.

I see your point, but I also think you are missing the real value of an architect. Refer to Martin Fowler's, "Who Needs An Architect?" (download the PDF from his web site).

What Martin has realized is that an architect is more than just a technical power hitter, or simply draws UML diagrams and spouts buzzwords. Personally, I believe that they must be able to personally code everything in their design, but more importantly, an architect is a coach and a mentor to the entire organization. That is where the long term value is for the architect. Allow me to elaborate:

The ability to speak to a large audience and be understood is vital. That means having a clear tongue, limiting your vocabulary (buzzwords), and fully engaging your audience.

You also have to be able to work one-on-one with developers to walk them though the development of solutions using technologies they don't understand. That has to be done as a mentor, and not by talking down to them. You have be ready and able to provide a demonstration, and to sit down right next to them as you walk them through the process.

Somewhere in the middle of all that you have to also be a buffer for the developers. As a point of contact for product management, you help control scope, and leverage the architecture to minimize any impact on the developer.

All of this requires a great deal of task switching; something that is very difficult for many technical minds to do. Pile on top of that the need to stay current with a rapidly changing market, and you have a position that very few people are worthy of occupying.

Speaking from personal experience, architects like this are not working 100 hours per month. They are working 100 hours per week.