I understand the rationale, but after getting the "maintenance" role a few times it feels me with dread. Usually when I get maintenance tasks it's for a system

I understand the rationale, but after getting the "maintenance" role a few times it feels me with dread. Usually when I get maintenance tasks it's for a system no one else wants / dares to touch. Evey time I feel like someone punched me in the face because it's always accompanied with the words like "we need someone else to know this system", "it's only for a little while" and the truth is that if you gain minimum competency in such a system you can say goodbye to more fun tasks - the maintenance of this old crap is your life now. No company will let someone with a knowledge of some obscure shit stop maintaining the obscure shit and move that person to a project that doesn't suck. Currently this is the 4th time I'm tied up in such a situation and while I was promised to be allowed to work on the "more fun" project "after 6 months so I can get my feet wet" the very last day of these six months I was told that one guy is leaving the company and that I can't work on the fun project because the obscure shit won't have enough manpower. The corporate machine works so slow that it will take at least another six months before someone gets hired. Hell, they're so incompetent that they don't even have a job posting yet.