Reusing the hangers is like reusing tyre valves to me. I always replace them because my experience is exactly the opposite of yours: they're old, loose and ready to fail, even if they survive the removal process. I hate doing things twice on my own stuff, and won't have avoidable comebacks on paying jobs. Cutting them saves time too. If I was going to spend OE prices, I'd upgrade to polyurethane hangers and some silicone spray to help fitting.
I dislike doing half a job to save some money right now, so tend to replace all the wear components at the same time like we recommend for Omega front suspension rebuilds.
I apply similar thinking to parts too: I've never found a reason to worry about oil brands, or for filters. I buy NGK plugs for preference, am happy with Bosch but won't touch Denso. I've had too many bad experiences with Apec brake pads so won't buy them, but don't care about the discs. I don't get any value out of the extra expenditure for premium tyres over mid-range ones, and often buy budgets. I avoid Intermotor where possible, especially ignition parts.
Some of this is down to me and how I use things. I've never been hard on machinery and some of the short life certain people here get from expensive consumables astonishes me even when I'm not paying for them