The costs of that 5 man Tactical Squad has been steadily ticking down. It was 90 points in 5th, 70 in 7th, it's now going to be 5 x 13 = 65. Which is the cost of units like Dire Avengers which can't take the Tacticals in a fair fight, so THOSE will have to be dropped in price, and so on... And because there's just not that many positive integers under 13 we get things sharing the same points cost that really, really shouldn't.
I remember reading a while back that points costs are not weighed against other armies' units, but are balanced internally within each faction. The faction's overall effectiveness is used to determine these points costs against other armies, and will be adjusted as needed during playtesting well before a new codex is released.
Imbalances happen because over time core rules can change, newer codexes introduce newer wargears, and models can be released with new rules independent of codexes, which can affect the balance of certain units.
I'm expecting this edition to be fairly balanced from the get go, however at the bottom of that article they said they were prepared to address points imbalances as time went on. So either way, I'm not concerned.