Guitar Pro tabs have time durations on every note (as described in the article), and can also be displayed in standard musical notation. It also has a whole host of articulation symbols, including the standard musical articulations (mezzoforte etc) as well as a bunch of guitar specific special articulations (e.g. artificial harmonics).

Printed guitar tab books also have durations and articulation symbols.

I agree that old fashioned ASCII art guitar tabs without durations aren't great.