You've come to this page because you've used the word "legacy" as if it is somehow a pejorative, perhaps talking about things such as "legacy softwares", "legacy systems", or "legacy applications", or perhaps simply employing the noun as an ad-hoc pejorative (e.g. "legacy MBR").
This is the Frequently Given Answer to such usage.
"legacy" is not a pejorative. Do not use it as such.
Please consult your dictionary. A legacy is something that is left to another in a will; a bequest of personal property. The word is derived from the Latin "legare", meaning "to leave by way of a will". That's it. By itself, it has neither positive nor negative connotations. (Although if something is left as a gift in a will, it is reasonable to deduce (a) that the testator thought that it had worth, and (b) that it was durable enough to have outlasted its owner.)
"legacy" is not synonymous with "outmoded", "old-hat", "inferior", or "undesirable". The use of the word as a subtle pejorative with those implied meanings is a trick of marketing folk, who wish you to step onto an upgrade treadmill, continually discarding your existing possessions in favour of buying All New Stuff, over and over again. Do not buy into this marketing deception by mis-using the word.
Conversely: If you really do mean "inferior" or "undesirable", then say so, explicitly. Do not be coy.
Do not be deceptive like the marketing folk. If you really mean "unfashionable" or "not á la mode", then say that. Be honest. Something that is no longer á la mode is not necessarily a legacy. After all, something need not be bequeathed to someone else for it to become unfashionable. Things can become unfashionable whilst one still owns them, and whilst one is still alive.
A personal example may help:
My grandfather, when he died, left me a large number of woodworking and D-I-Y tools. They have proven to be exceedingly useful, and I value them for their utility. Many of them are superior to the tools that I myself possessed before he died. However, some people would have the phrase "legacy tools", which describes exactly what my grandfather left to me, connote the idea that these tools are somehow inferior, substandard, antiquated, not useful, and in need of modernization or replacement.
My set of wood chisels, as good today as when my grandfather first purchased them, would beg to differ with that idea.