There is a stigma attached to doing this so it is not initiated without very good reason. Many institutional investors and mutual funds, for example, have rules against purchasing a stock whose price is below some minimum, perhaps $5. An extreme case would be when a share price has dropped so low that it is in danger of being delisted from its stock exchange.
It is also possible that a reverse stock split could be used as a tactic to reduce the number of shareholders. In a hypothetical 1-for-100 reverse split any investor holding less than 100 shares would simply receive a cash payment and no shares of stock. If the resulting number of shareholders has then dropped below some threshold, it may be placed into a different regulatory category.
Typically, the stock will temporarily add a "D" to the end of its ticker during a reverse stock split.