That's exactly why the play-ins were created, to maintain the season's competitiveness from the start to finish. Look at how the teams from 5th seed down to the 11th seed in the Western Conference, they are tightly competing for either a secured spot in the playoffs or secure a spot for the play-ins. Lakers, Warriors, and Rockets are now has a close competition to secure a play-ins spot, with the Rockets and Warriors being close to each other with 2-3 games apart. Every game left for these 3 teams are a must, otherwise one of these teams will get behind and drop to the 11th seed. The Rockets are on 11th winning streak, so the Warriors must watch out as they need to get a consistent W's before the season ends.
When this was implemented, I kind of hated it since getting into the playoffs is much harder now with the play-in. Way back, you just needed to secure the 1st to 8th spot and you were good to go, but now that you have secured the 7th or 8th spot, you can still slide down to the 9th spot and cannot go to the playoffs. But looking at it now, I can see the beauty in it and why they implemented this so that every game has more meaning, especially for those players that are in the play-in spot. In the past, if there were few games to be played, some of the teams would rest some of their players so they would be healthy when the playoffs came.
Overall, play-in tournaments make the league more competitive since teams will value the game more. I think the downside of this one is that after the 82 games, records don't count; one game can change everything, just like what happened in the Miami vs. Hawks last season. The Heat had a better record, yet the Hawks became the 7th seed because they beat the Heat.