What are the reasons that companies _MUST_ have a web site? Please
find articles that demonstrate the reasons for large companies to have
a web site.

Top 6 reasons why a website is crucial to your business according to
Jamie Kiley (http://developers.evrsoft.com/article/web-design/content-webmaster-issues/6-reasons-why-a-website-is-crucial-to-your-business.shtml)

#1. A website increases your credibility.
#2. A website makes your company visible anytime, anywhere.
#3. A website makes it easy for people to refer new customers to you.
#4. A website is a powerful sales tool.
#5. A website increases the value of your advertising.
#6. A website helps you stay in contact with potential customers.

I agree. Being able to take orders 24 hours per day, globally, is a
very good reason that a company have a website. 24 hour technical
support for a product is another.

Of course, it will depend on your industry, to be sure, how valuable
the website is for income, but it certainly is the only true way a
client may 'get' what you're selling when they can't talk to a live
person on the phone.

It also enhances your corporate identity and provides a way to provide
interractive content in a quantity that can't be bought on TV, radio
or newspapers.

As an alternate opinion, If your web site contains only generalities
instead of details and some of the links don't work well, it makes me
suspicious that the products and services may also be poor.   Neil