I think its simply to make the shares appear better value. People buy more shares, Ryanair gets more dosh (to spend on new 737s and flight crew, hopefully)
You are correct when you say it makes the shares seem better value. For example, Cable & Wireless use this tactic every time their shares hit £10, although with the fall in Telecoms stocks it may be sometime before they reach that level again.
Ryanair do not benefit from people buying shares. Once a company has floated the shares traded give no financial benefit to the company. The only way Ryanair can make more money from shares is issuing more stock. Generally companies will retain a holding internally that can be used to raise cash or for bonus or share option schemes. Alternatively they can have a Rights issue, similar to BT earlier in the year.