A lot of the old runes, especially before the whole Keystone phase, were just "more damage". The object of the numerous mastery updates - and recently runes reforged - was never to make them less about damage, it was to make them more contextual and interactive.
Seriously. You'd see stuff like +2/4% crit damage, +0.5/1/1.5/2/2.5 AD / AP equivalent, +0.5/1/1.5% damage, and variations, all throughout the old mastery trees.
This eventually became the keystone masteries. Those did the same thing, but more interesting. I.E. 1% damage for each individual champion killed, upto 5%. 1% damage dealt, stacking once every 3 seconds, upto 3%. +4% damage on abilities (not ad or ap) or +4% attack speed.
The key difference is that the static and not interactive, but also omni present and invisible stat buffs became more interesting. They became more powerful (1.5% damage boost as a max, vs 3% or 5%) but they also became more conditional (enemies killed, duration of combat).
Runes Reforged is a continuation of this system. The damage - or defenses - have been buffed up and made far more meaty, but it's been better fleshed. So rather than just getting +5% damage, you get an additional nuke for landing three separate sources of damage for in a short window. Rather than gaining +17% attack speed constantly, from difference sources, you can active a huge attack speed boost for a short duration.
The reason for this is pretty simple. When your bonuses are all small but permanent stat boosts, it's pretty easy to math out what's best in each situation. Plus they're boring as shit. When you make them similar but contextual, you begin to encourage active thought about how champions operate, how YOU operate said champions, and also how the champions they will be playing against operate.