Would Bitcoin be more secure against extremely powerful computing tech with more words in the dictionary list, a larger number of seed words and perhaps a longer BTC address/privkey?
If you extended your seed phrase from 24 to 50 words, it wouldn't make it more secure in a case of a brute force. The attacker would have to either search among 2048
24 or 2048
50 different combinations. But, an attacker wouldn't need to brute force any of the seed phrases above to steal your money; he'd find it less demanding if he went straight by brute forcing 2
160 RIPEMD-160 hashes.
Quoting one of my posts:
I'm just adding the numbers
decimally:
2^128 = 340282366920938463463374607431768211456 (12 words)
2^160 = 1461501637330902918203684832716283019655932542976 (RIPEMD-160 hash different combinations)
2^256 = 115792089237316195423570985008687907853269984665640564039457584007913129639936 (24 words)
I believe that the seed system works fine. You shouldn't think about a dictionary list with more words, but rather with bits. A twelve words seed phrase is a 132 bits representation in BIP39. A twenty four words seed phrase is 264 bits representation. I highly doubt if these numbers can be characterized as “weak”.