I guess the biggest problem with printing directly on the build plate is prints can’t be oriented at an angle without supports to minimize the peel forces.
For flat plates like what you have shown aren’t an issue, but I think it might be for most the parts I’ll be printing.
But yeah - if you use this often - I would seriously recommend a TEC. One TEC with cooling fan (the hot side of a TEC needs to be cooled) is likely the cost of a compressed air can - and will last much much longer. Probably way more environmentally friendly too.
I know what you mean about FDM printers. Once my heated bed cools prints usually break off on their own.