It's not powerful enough for easy ports, it's as simple as that. Not many devs are willing to go in and do alot of work, downgrading textures and shadows and such to make their game run on Switch. If Switch had been powerful enough to run the same games that PS4 runs at 1080p and XB1 at 900p at say 540p with no other downgrades, I'd think we'd be seeing alot more ports. But it requires more work than just a simple resolution drop the get most AAA's to run on Switch.
They basically had two options, they could release a separate handheld ($199-249 Vita+) and console ($299-399 PS4 clone) or release a single device that falls somewhere right in the middle ($299 hybrid).
With the first option they could have likely gotten some more of the big AAA titles like Call of Duty, Assassin's Creed, etc. but what would cause people to buy this console over the established PS4/XBO or their new upgrades? It would be Wii U all over again where these games dont sell well and 3rd party support disappears within a year outside of things like Just Dance so it becomes a console bought solely for 2-3 big Nintendo games each year.
With Sony out of the handheld picture, their new handheld device could probably consolidate the 3rd party support of 3DS & Vita into a single device so strong Japanese & indie support but that's easily off set with the increased dev time/cost for Vita/PS4 level hardware compared to 3DS/Wii U so 1st party output would take a hit on each platform compared to their predecessors.
Overall you would probably be looking at a repeat of the 3DS/Wii U numbers or possibly worse so even though Switch isn't getting all the AAA titles that PS/XB get, it's in a much better situation than if they went with a powerful console.