I have no prejudice about templates. Why would I?
I did one of my first projects from a block on Quilter's Cache which used templates. I had no preconceived notion about whether they were bad for me, and if I had made better ones the blocks would have been better maybe, but they were clever and get a lot of compliments.
I just bought a Sue Garman BOM pattern Washington Medallion which may kill me but the paper-piecing templates are fine, the problem is my lack of skill to go inside-out upside-down backwards in a consistent pattern.
I finished a landscape quilt where I made my own templates from modified photographs of the things I was trying to copy. I did a couple simple appliques with templates.
So fine, I'll pay for a template.
A template is more accurate than a measurement - ask any carpenter who has ever used a story-pole. Marking is more accurate than a ruler.
But I draw the line (pun not intended) at gimmick rulers. Especially if the pattern seller tells you that you have to buy their proprietary ruler. Nonsense. Every 'specialty pattern' ruler I've seen has been doable with a ruler, or a hand-drawn mark on a ruler, or a template.