Sentence 1 doesn't work because the while-clause comes second. A while-clause expressing a contrast (a significant distinction or difference) can occur in either position, but when it expresses mild concession it must come first.
Sentence 2 has the while-clause in initial position, which is where it can express mild concession as well as contrast. But since the two situations in Sentence 2 are clearly in opposition (the wetness of the streets is unexpected), they do not qualify as mild concession; they require a marker of full concession (see below). That's what makes Sentence 2 feel not quite right.
The subordinating conjunction "while" has three very different functions. The principal function of "while" is to introduce a clause of duration, e.g. "He holds the lantern while his mother chops the wood"(the title of an old song)."
The second function of "while" is to introduce a contrast "” a significant difference between two things. Clauses with "while" showing contrast may occur in either order. (Examples are from Google.)
"” Some of them [the athletes] will be familiar names while others will be making their mark on the world sports scene for the first time.
"” Most participants will be individual children while some will be sibling groups of two.
"” While the boomers will be over-educated (there will be 30 candidates for every middle-management job, an economist with the American Society of Training and Development predicts), the newcomers won't be.
Clauses with "while" may also be used in a third function: to express mild concession, but only when the while-clause comes before the main clause:
"” I've had to see a chiropractor very frequently for the last two months and while it's been improving a lot, it seems to have become a chronic problem... (NOT *"It seems to have become a chronic problem, while it's been improving a lot")
"” She can be intensely serious when she has to be. While she's been kidnapped
a lot, she has has saved Mulder's a** more than a few times.
"” While I've been told it's a widely known fact within our circle of friends that the groom has always hated this odious character, it still concerns me to some degree that people at the wedding will look at me like some psycho ex...
"Although" expresses full concession. Concession has to meet three requirements, according to Huddleston and Pullum (2002)*. The requirements are here paraphrased:
1. Both statements are true
2. The idea in the subordinate clause might lead one to expect that the main clause will not be true
3. In fact, the idea in the subordinate clause does not make the idea in the main clause untrue. It makes the idea in the main clause surprising because it is unexpected.*
"Although" and "even though" fit this description of concession. "While" in initial position does express mild concession, but not full concession. When it is in second position it is interpreted as showing contrast (unless, of course, the relation is one of time).
*The Cambridge Grammar of the English Language, p. 734