Normally Ajax coaches come from within the club. Ten Hag roots are in the East of the Netherlands, close to the German border. You think his English is horrific, his Dutch is even worse. He is a farmer boy with no flair at all who more or less out of the blue became the Ajax coach. He started with a lot of scepticism from both media and fans.
Now Ajax is not a European top club but I am sure it's definitely one of the most difficult clubs to be the manager of. Defensive football is just not being accepted. Both attractive football and results is what the supporters demand, nothing less. I can imagine Ten Hag didn't feel like he was finished yet at Ajax and wanted to settle in a bit more and further improve the team.
I think Spurs should be glad with his attitude. If he was as 'ambitious' as you say, he will be gone to City within a year after 'doing' Spurs.