Woah, that is an AWESOME quote! From a philosophical standpoint, of course. Your question is so very broad... I will do my best to get to all of it.
Is religion a serious impediment to the development of mankind? I do not see why it would have to be. Historically, it has been good and bad. The Oracle at Delphi was instrumental for Homer, Plato, Socrates, etc. I'm not sure if ancient Greek philosophy would have evolved without the gods of Olympus. Think of all the great feats that were organized around religion... the pyramids of Egypt, the building of Rome. Do you think geometry would have progressed as fast if ancient engineers were not trying to figure out how to make sturdy pyramids?
On the contrary, we most likely would have colonized Mars by now (or destroyed ourselves completely) had the Dark Ages not happened. Our cars wouldn't have V8s; they'd have warp drives. We'd all have stargates in our toasters. Our gardens would have perpetual motion machines, and our bathrooms wouldn't have toilet paper... they'd have three seashells. Okay, a bit of humor has served its purpose.
Historically, religion has been both an impetus for development and an impediment. That is most likely true still today. Therefore, you cannot make a good case that religion is a serious impediment as some type of axiom in a grand model of human behavior or theory of everything.
Why do some religions emphasize self-suffering as a virtue? Remember that virtue, in its original sense, meant being reasonable. When most of those ancient religious texts were written, suffering was COMMON. Enjoying life was not possible for 99.999% of people in the manner you mean. I'm not saying life was suffering for everyone; I'm saying that people had to make the best of their situation. Learning how to feel freezing temperatures like warm summer breezes made life easier.... easier to enjoy. Even for the .001% who knew enjoyment of life as you mean, they still had a heck of a time! No antibiotics... no knowledge of bacteria/parasites... for the most part no refrigeration... heck, maybe not even any garlic for their alfredo sauces!
Religions were and are organized belief structures, and I purport that these "embrace suffering" clauses were built in to make life easier. Learning to deal with adversity kept people from all just committing mass suicide... it provided a REASON to live. Virtue... reason. Do you see?
Now, finally about your quote... I am sure the quote is meant to be literal, but let's be a modern optimist for a moment... it might have been a way to keep the widow from being raped repeatedly. You don't know if the widow is 19 or 90. It sounds terrible to keep a 19-year-old widow from remarrying, but it sounds horrible for men to ravage a 90-year-old widow. The 90yo would most likely not want to remarry. As men and women would share the same Hindu faith in the culture in question, this protected the women. Therefore, it may have served a good purpose at the time. Some got the short end of the stick, and some were spared great hardship. That duality is quite common in ancient philosophies.