When Apple was in the high $600 or so range, it split 7-for-1 and made it more affordable to purchase more shares for less, even though the value was technically the same. I see companies like Google are extremely high per share and am wondering why or why not they would or wouldn't split their stock right now.
A stock split is usually done by companies that have seen their share price increase to levels that are either too high or are beyond the price levels of similar companies in their sector. The primary motive is to make shares seem more affordable to small investors even though the underlying value of the company has not changed.
It is often claimed that stock splits, in and of themselves, lead to higher stock prices; research, however, does not bear this out. What is true is that stock splits are usually initiated after a large run up in share price...stock splits do increase the liquidity of a stock; there are more buyers and sellers for 10 shares at $10 than 1 share at $100. Some companies have the opposite strategy: by refusing to split the stock and keeping the price high, they reduce trading volume. Berkshire Hathaway is a notable example of this.
Something more to munch on, Why Warren Buffett Is Against Stock Splits.
A reason not to split your stock is that the value of the company might fall back again, and if its stock price falls below $1 it will be delisted from the NYSE. So if the value of your company grows tenfold so the shares go from $5 to $50, you do a ten-for-one split, and then its value shrinks back to where it started, you're off the stock exchange.
The reason to do a stock split is to get the price of the stock down to an affordable range. If your stock costs $100,000 per share, you are seriously cutting in to the number of people who can afford to buy it.
I can think of two reasons NOT to do a stock split. The biggest is, Why bother? If your stock is trading at a reasonable price, why change anything? It takes time and effort, which equals money, to do a stock split. If this serves no purpose, you're just wasting that effort.
The other reason is that you don't want to drive your stock price down too low. Low prices are normally associated with highly speculative start-up companies, and so can give a wrong impression of your company. Also, low prices make it difficult for the price to reflect small changes. If your stock is trading at $10.00, a 1/2 of 1% change is 5 cents. But if it's trading at $1.50, a 1/2 of 1% change is a fraction of a penny. Does it go up by that penny or not? You've turned a smooth scale into a series of hurdles.