Because size/weight/shape of telescope/mount etc are vastly different as primary eyepiece design parameters (focal length, AFOV, eye relief, glass, cost, ...) are vastly different.

If you demand optical engineers "one size fits all or telescope balancing issue by eyepiece" type requirement as mandatory design parameter, I suspect you will be disappointing result of product in terms of optical quality, mechanical robustness, price etc.

I believe free to design anyway you want is much better solution so that we consumers can choose whatever our liking

If you sort my weight measurement in eyepiece focal length, it tells something: Some eyepiece weight is more than 10x than other with the same focal length.

Code:


Partial list where it is interesting:
 grams   F/L model name
 237.0  16.0 WO-UWAN
  84.0  16.0 ZAO2
 722.0  17.0 TV-Ethos
 179.0  19.0 TV-Panoptic
 358.0  20.0 Pentax-XW
 678.0  22.0 TV-Nagler
  68.0  23.0 SV-Plossl
 298.0  24.0 Hyperion
  81.0  25.0 Zeiss-Ortho
  75.0  28.0 Siebert-UW
 958.0  28.0 WO-UWAN
 771.0  30.0 BW-Optik/Zeiss
 291.0  30.0 TMB-Paragon
 160.0  30.0 Tak-LE
 354.0  31.0 Hyperion
 308.0  32.0 Edmunds-RKE
 175.0  32.0 TV-Plossl

Tammy