And what does being "poor" have anything to do with it being a launch title? How you missed Knack and Killzone and added Bloodborne and Order 1886 is beyond me.
It matters because launch game or not, efforts like Knack and Killzone weren't well received, it's that simple. If you're implying that next-gen early adopters are desperate enough for content to buy a game simply because it's new and on that system only, well that was probably more true in the past, but entertainment was more fragmented back then, too. Crossover wasn't as big as it is today. If a launch game isn't well-received it doesn't matter if it's an exclusive or not, that bad reception will potentially harm its uptake and make a lot of people simply wait for other games to come.
Also, historically speaking, the only platform holder whose 1st party launch games have consistently been the biggest drawers for early platform adaptation is Nintendo. With others it was either very region-specific and sporatic (SEGA, Saturn Japan launch Virtua Fighter), or really driven by 3rd-party content (PS2 launch, Dreamcast launch, 360 launch etc.). 3rd parties have been prioritizing more platform support as the years have gone on, not less, so that is probably going to extent to cross-gen efforts for the first year or so.
Speaking of Killzone and Knack, Killzone in particular did okay for launch but I'm almost 100% sure the then-launch Battlefield and COD games greatly outsold and outscored it, including on PS4. And those two were cross-gen games. So the point is, whether next-gen launch titles are cross-gen or next-gen exclusive doesn't have as big an impact on the quality of the game or its perception in being "next-gen" compared to other titles on that platform as you think. And with the multimedia features of modern systems, if a 1st-party launch game is next-gen exclusive that doesn't automatically guarantee it's worth a buy; people could still pick up that next-gen system but put the money they'd spend on that game towards another game, or multimedia purchases to use on that next-gen system instead.
That's really all I'm saying.