1. It's (physical) software isn't bad.
2. You forget about the digital advantage for PS4 compared to every other system in Japan
3. PS4 literally just had a huge release in MHW :).
For 1: compare 2015 and 2016
2015:
01. 3DS - 18.438.698 <49,37%
02. PSV - 5.205.609 <13,94%
03. PS4 - 5.114.598 <13,69%
04. PS3 - 4.185.655 <11,21%
05. WIU - 3.926.000 <10,51%
06. PSP - 304.545 <0,82%
07. XB1 - 117.378 <0,31%
08. 360 - 55.261 <0,15%
00. ALL - 37.347.744 <100,00%>
2016:
01. 3DS - 14.780.505 <45,93%>
02. PS4 - 8.672.086 <26,95%>
03. PSV - 4.823.793 <14,99%>
04. WIU - 2.206.047 <6,86%>
05. PS3 - 1.629.591 <5,06%>
06. XB1 - 66.771 <0,21%>
00. ALL - 32.178.795 <100,00%>
For 2015 Vita started with triple the install base and still had double the install base of PS4 by the end, yet PS4 sells similar physical software and definitely sold more total software with digital. 3DS had 17x (start) and ~10x (end) the install base and sold only 3.5x as much SW.
For 2016 Vita had double (start) and 33% more (end) yet PS4 almost doubles the physical SW and much more with digital. 3DS had ~10x (start) and ~5.5x (end) and yet its entirely possible that the PS4 sold 10m+ SW with digital.
The situation has only improved for PS4 on the SW front, imo it is the HW that is lagging behind in contrast to your assertion that the SW is.