My two cents (no, let's make it twenty, because this will be a long post):
First off. I don't think repetitive or repeated choruses is a problem in Maiden's music in general. I enjoy most of the songs discussed in this thread. There are a few where the repetitiveness takes away from my enjoyment, and I'll come to that later in my post.
A repeated chorus is not the same as a repetitive chorus (but a chorus that is repeated more than usually makes the song repetitive - again this can b). Some Maiden choruses are repetitive lyrics-wise and varied music-wise, a few are repetitive in both respects, but many of these are still good. Repeating the same lyrics over changing chords makes for a good singalong, helping the band creating a good live experience with the crowd. Let's look at some examples, including some songs mentioned in the thread already:
The Evil That Men Do: The chorus consists of the same lyric line repeated four times. The first and third line share the same vocal melody, as do the second and fourth. The drumming varies throughout, which means the chorus doesn't sound repetitive music-wise. When it's done this way, it doesn't matter that the chorus is simple lyrics-wise. Moreover, this type of chorus (the same line repeated four times, with changing chords and/or changing rhythm section) is quite common in Maiden songs. I can mention SSOASS the song, Caught Somewhere in Time, The Clansman, and many songs from the post-2000 era, for example The Wicher Man, Blood Brothers, No More Lies, and Brighter Than a Thousand Suns. All of these are songs I enjoy a lot.
Now let's take a look at the few songs where I personally find the repetitiveness a problem - a reason in itself for not rating the songs highly:
The Angel and the Gambler: This song has a chorus where there is little repetition within the chorus, but the chorus is sung 22 times! Even with the variation in intensity and rhythm guitar chords, this becomes too much for many people.
The Mercenary: This song doesn't really feel like it has a defined chorus. The line Show them no fear, show them no pain is repeated many times, but in this song there is very little variation in the rhythm guitar/bass/drums underneath the line. It is the same throughout, except for the last two times the line is repeated in the song (out of something like 20, feel free to listen and come back with the exact number).
Don't Look To The Eyes of a Stranger: Like The Mercenary, it doesn't feel like it has a defined chorus. How many repetitions of the title should be counted as one chorus? One round of "Don't look to, don't look to, don't look to the eyes of a stranger"? It feels like the repetition of that line will never end, and once it does, it goes on to a very generic melody with drumming that must be the reason why somebody jokingly stated that it was Steve Harris who did drums on VXI.
One final point: I can't come up with any other examples than the final three songs I mention, where a defined chorus is sung more than twice in a row. Or - there is one more, Stranger in a Strange Land where the chorus is repeated multiple times during the fadeout. But in this song it has a guitar outro solo underneath. And singing the chorus twice after the last verse is a very common thing in music across genres.
To close this post: I don't think repetitive choruses is a problem in Maiden's music in general. The examples where it takes away from my enjoyment of the song are few. In most cases it just makes for a good singalong.