Web standards, Google, Microsoft and browsers
Another reason for efficient layout is that I've been investigating putting up Google's Adsense on my web site in the hope that my web site (www.linuxha.com) will earn enough money in a year to pay for it's expenses. I don't intend to go crazy with ads. I don't want the ads taking up a lot of space (they'll be text ads) and there will only be one at the top (none at the bottom or the sides of the page). It's not the main purpose of my web site which is home automation and Linux!).
Lets say the web site costs me $200.00 (US)/year for expenses (that's pretty close). I happen to get approximately 50K hits/year on the just the main page. If 2% of the visitors (1 in 50) click on the Google text ads the pages will pay for themselves (50K x $0.20 x 2% = $200.00). I really don't expect that the web site will bring in a lot of money. If it doesn't bring in any money then there's no great loss as I would have been paying for the site anyway.