It has become fashionable to gripe about the Pacers' use of the 3pt shot.
Let's take a moment to reflect on a couple of facts.
Greater reliance on the 3pt shot is an NBA wide trend. All teams are using the 3 more, and the trend continues from year to year.
The reason the Pacers (and everybody else) are ussing the 3 more than in the past is that players are getting better at shooting it, and so it has become a very potent scoring tool.
Plus it spreads the floor!
Next, the Pacers are not, repeat not, out of line with the rest of the league in their use of the 3. The Pacers have never been the top user of the 3 in any season:
If you follow the yellow markers, you'll see that the Pacers trend in using the 3 is going up over the long run -- not just under O'Brien. Look back at the years when Rick Carlisle was coach, and you'll see that the Pacers increased their use of the 3PA during his years by a wider margin that O'Brien has done subsequently.
The bottom line is winning, of course. And the evidence of the past 20 years is that 3pt attempts are not just for losers. I know I've read the argument that only under-skilled teams like the Knicks, Warriors and Pacers use the 3pt shot, as a way of trying to make up for other deficiencies. That is probably true in particular cases. But over the long run, the 3 is used just as much be winning teams as by losers:
Each dot depicts an NBA team since 1990, aligning the team's reliance on 3PA and its season winning percentage. The complete random placement of the dots shows that there isn't any relationship between shooting 3s and winning (or losing) games.