If you're OCD (there's a strong correlation between 'collecting' hoarding, and obsessive compulsive disorder) then buying MISB is a really important selling point. You may not open the toy, but if you decide to pare back your collection at some point, having had the seal broken and retapped raises suspicions, and you really won't get that absolutely crazy 'I must have it now' premium you get on some toys. I say this not disparagingly, because I have paid extraordinary amounts for G1 MISB or MOSC toys...... but could never bring myself to purchase a MIB toy, and have sometimes been hoodwinked with a listing that says misb and you find the tape has been broken, or resealed (revealing is the worst, because you don't know what they did to it BEFORE they put it back in the box). While other people can save a fortune by buying loose toys, OCD people could pass on a holy grail item because its possibly contaminated. I see beautiful pieces like that on Mandarake that I could never cope with touching.
I can completely understand where the sentiment 'why would it matter' (on a doubletaped/resealed item) on a toy purchase comes from. But if you think that then you're probably healthy 
Reselling might not be your goal right now but it might be at some point in the distant future. It also means that the buyer (of a MISB item) will know that the toy hasn't been played with, damaged, possibly broken and resealed. Though I have heard horror stories of people buying MISB g1 with factory errors or broken parts!
On the lookout for MISB Headmaster Highbrow, Takara or Hasbro. I'm sure I could make you a sweet deal!