Time and Resources: Generating a vanity Bitcoin address is a computationally intensive process that requires substantial computing power and time. The more complex the desired pattern, the longer it takes to generate the address. This process can be resource-consuming and may deter some users.
It depends on how long the characters that you want to customize, the more the characters, the more computational power needed to achieve this in a show time. On computer (CPU), for just 3 characters for uncompressed legacy address, it will take only few minutes like three minutes, while 5 words for segwit will take just some minutes too. But the more characters that you want to customize, the more it will take more time.
1. Does the desire for a personalized address outweigh the privacy concerns associated with generating a vanity Bitcoin address?
Privacy first. If you are not savvy enough to generate vanity address, do not generate any. Get a reputed open source noncustodial wallet tand generate your keys and addresses using the open source wallet.
2. Is the environmental impact of the computing power required to generate vanity addresses justified for personalization purposes?
When discussing about vanity address generation, there should be any reason to relate it to environmental impact. Most people are using normal bitcoin address generated on noncustodial wallets.