I think there are few points that might have been wrongly stated in your mail. The profit for the promoters is never the stated (only implied) reason for IPO. Promoters are (at least supposed to be) there to stay with the company. This is in contrast to PE players (like VCs) who really have IPOs as exit strategy.
As for underwriters (i-banks), they have a huge responsibility (much more than what your mail seems to be giving them credit for). Firstly they have the sole responsibility of bookbuilding process (which gives them a rough idea of what the issue price will be). A bull run is just one of the factors which decides whether or not the entire issue would be sold. Remember that normally 60-70% of the issue (or even more) is reseverd for institutional investors, and these investors don't just look at the bull (or bear) run. They do a 'fundamental' valuation of the company (by Discounted cash flow method, residual operting income, comparable ratios such as P/E etc.) to find whether the issue is worth investing in.
There *have* been issues in the past which were not fully subscribed (despite the bookbuilding process!!) since investors opined that the issue was overpriced. And while it is true that the promoters select the underwriters, one of the *big* things that all promoters look for in an i-bank is whether the i-bank has been able to carry (100% subscription) all the IPOs in the past. Just think about the kind of damage it could cause the company (in terms of reputation) if its issue was undersubscribed. Hence, there are quite stringent penalty clauses attached for the i-banks, if the issue does not get fully subscribed.
And to ensure 100% susbcription, i-banks under-price the issue so that the investors consider it an attractive buy.
In fact, even after the trading starts, the underwriter 'supports' the price (and hence the term support price) for few days. Of course, the underwriters, for all this risk that they take, they charge a hefty fees.
Just google on IPO underpricing and you will find lots of information. One of the articles is at:
http://www.ecb.int/pub/pdf/scpwps/ecbwp428.pdf