There are already Talents on every Career, on several tiers, that are less-than optimal picks or downright not worth it ever. This kind of system would also require balancing Talents against everything else (even if point cost could be used as a balancing method) instead of just per-tier. So there would be way more work in balancing them. In addition, some things would produce horrible results in combination (particularly several Talents picked from level 15 and 25 tiers). A Slayer with even more DR? Okay, he’s tough and agile enough already, but whatever, still not on par with IB. A BH with both reset-on-melee kill and free ammo? The first one was moved to a Talent for a reason. A Merc with all three lv25 options? Yeah, I’d take it.
For all these reasons, I have reason to suspect a point-buy system would both reduce effective builds (while giving an appearance of more choice) and break a lot of things. And those are reason enough to say “not a good idea”.