A Staunton set where the Rook is taller than the Knight is uncommon. Do you know of many others besides the HoS Collector Series? Looking at it now, it doesn't bother me at all. I kinda like it.
It looks like HoS "fixed" this with the follow-up Collector II Series. I actually prefer the first one with the taller Rook.
https://www.houseofstaunton.com/the-collector-ii-series-luxury-chess-pieces-4-0-king.html
You are not the only one. I don't like it as well. Staunton sets usually have shorter rooks.
I have never seen an HoS Collectors set with the rook being taller than the knight. The only time I've seen a set from HoS having taller a rook than a knight would be the Morphy set reviewed by @Cgrau. https://www.chess.com/forum/view/chess-equipment/house-of-stauntons-morphy-set. The photo below is compliments of @CGrau.
When did you buy the HoS Collectors?
I have the Collectors 3.75 in padauk from 2019 and the knight is definitely not taller than the rook. The knight's nose is the same height as the rook. The knight's mane is what makes the knight taller.
I also owned the HoS Collectors 4.0 for a couple of days. That rook is shorter in that one as well. The knight and rook are shown in the below photo.
I learned chess using my uncle's Windsor Castle chess pieces. So I prefer sets with rooks slightly taller than knights.
I only have seen where the knight is shorter than the rook in BCC popular sets. I also prefer the knights taller than the rooks yes.
That could be why. Most of the sets I have seen from HoS were from 2017 on. Perhaps HoS did it differently before 2017. Post some photos tomorrow. I would love to see them.
Btw, you should ask HoS to see if they have replacements. They might have some sitting around. Also, have you considered asking HoS about the height of their new rooks. Perhaps the new rooks are shorter. If so maybe you can purchase 4.
The set was purchased in 2012, boxwood / rosewood Collector Series, 3 inch King -I have a nice wooden box with the set info on the bottom. I also have a Collector set with ebony dark pieces and those rooks are shorter than the knights. . . . Maybe I bought that one at a different time, I really don't remember. I've been using the rosewood set, but I think I'm going to put it away in favor of the ebony, I like the shorter rooks . . .
The Chessbazaar Richard Whitty chess pieces are one of my 3 favorite sets. They all have large, tall rooks. The king is 3.75", the rook is a tall 2.7" ,, the knight is 2.5" tall. I use a board with 2" squares. The rook was the most powerfull piece for more than a thousand years. It still is the second most powerfull piece. I like tall, robust rooks . I dislike short, small rooks . The size of the piece should be determined by it,s relative strength.
In 1900, the British Chess Company issued their last two designs, a reissue of the Imperial Chessmen and the Improved Royal Chessmen. One of the distinguishing features of the latter was that they turned away from the customary approach of making the pieces linearly smaller starting from the king. The British Chess Company rather pursued the approach of aligning the size of the pieces with their playing value, which led to a clear enlargement of the rooks to signal their higher playing value compared to the knights and bishops.
Am I the only one who HATES when the rook is taller than the knight? I have a Collector set, actually more than one, from HOS and I really like the shapes, except for the height issue . . .