It is absolutely worth it to get better equipment in warzones. Bolstering (the name of the mechanic that scales your stats) does two things.
It scales the skills you have to their level 50 versions, if they scale with level.
It modifies some of your current stats, primary stats, health, damage, etc. to level 50, based solely on your level. This is a multiplicative scalar, not an additive one.
For example (with made up numbers): Suppose at level 10 you have 100 base strength. At level 50, you have 500 base strength. The Bolster system would apply a 5 times multiplier to your current strength, so if you only have a total of +10 from gear, you end up with 550 str. However, if you keep yourself in purples, and have +40 str, you would end up at 700 str instead.
This essentially means that your gear "scales" right alongside your level, and if you are in all purples, you could have higher stats than a non-Bolstered person in greens/blues.
Bolster does not give you new skills, nor ability points to spend in your advanced class trees. Also, unless you buy PvP-specific gear, you don't get expertise, which makes a huge difference.