Bandwidth is a very important requirement to ensure good application performance the higher the better, in general. But one has to remember that throwing bandwidth when there is a response time issue is not always the right thing to do.
Everybody agrees that bandwidth has gotten cheaper and cheaper in the last fifteen years or so. In the US, for example, homes which used to access Internet at 19.2 kb/s or 56 Kb/s during the early days of Internet have downstream speeds of 8 Mb/s or more via cable modem service. Some homes may have even 50 Mb/s or higher if they have fiber to home. With these higher speeds, US homes (and homes in other many developed countries) are enjoying applications such as high quality streaming video (like Netflix).
However, the bandwidth growth story on the enterprise side is uneven at best. It is true that most companies do have very high speed access to the Internet (hundreds of Mb/s or several Gb/s). Companies have headquarters, data centers, and tens or hundreds or thousands of remote sites scattered over a geography; depending on the size of the company, this scattering could be state-wide, nation-wide or across the globe. All these sites have to be connected via a private network that is highly available, highly secure, provides good performance, and most importantly, cost effective to build and operate.
Small and medium sized businesses have exploited high speed Internet and VPN technologies to build high speed private networks. But many bigger corporations have their networks based on Frame Relay or MPLS technology or even leased lines to some sites. This is because the telecom providers offering these services to enterprise customers guarantee high availability, high security, Quality of Service and other features. Many companies, especially in the financial sector, are reluctant to use Internet-based VPNs to carry their sensitive data.
Large enterprise customers can have hundreds or even thousands of sites (some retail chains have 20,000 or more remote sites). Most of these sites could be low speeds like 64 Kb/s or fractional-T1s. Major sites may have T1 bandwidth. Also, telecom providers have multi-year contracts with the enterprise customers making it hard to upgrade speeds although they may be getting cheaper. The prices of these enterprise grade links are not coming down fast enough as the telecom providers have legacy technology and older provisioning systems for services such as Frame Relay. Also, the local access lines for these services are not cheap. Because of the large number of sites and the incremental cost of upgrading from 64 Kb/s or fractional-T1 to full T1, many enterprises may still continue with these low speed circuits.
But the worst part is that these low bandwidths have to be shared by tens or hundreds of employees at the remote sites. That means the actual bandwidth available may be tens of Kb/s per user. Compare that with the cable modem speed of several Mb/s per user at home!
This situation with the large enterprise customers is changing but slowly. Hence we can expect APM issues to continue to exist for a long time with the enterprise customers.