You haven't. It's no different to the Russian or Chinese transfer window being open at different times to ours now. You can only buy when your window is open but you can sell whenever another League's window is open.
I don't think thats true at all.
The end of August would just become the end of July and 90% of the issues would remain.
Also, how pleased would all the clubs be if other clubs were sniffing around their star players near the end of the season because they had so little time to plan and complete transfers. The CL only finishes at the very end of may and then in a world cup year you would have a few weeks to either sign players or you would have to wait until after the WC and use the 2 weeks then to complete deals. Almost no deals happen during a WC because clubs don't want to sell players that might have an amazing WC that boosts their price and countries don't want to have to try and prepare and compete in the WC with half their team being involved in transfers.
You would end up with effectively a 4 week transfer window split into 2 week sections a month apart. Clubs would hate it, players wouldn't be so keen and it would generally be a nightmare to get deals through the door.
Oh I know but it gives you nearly another month of leeway. Its just another plus point for keeping the window open a bit longer.
Exactly. You have the power to keep players if you want. Its always a choice.
Seeing as it's being reported that most clubs are in favour of a shorter transfer window it's clear that they won't hate it or at least that it doesn't concern them. Transfers don't take months to be completed and clubs know this. They can and will be completed much quicker if they had less time to do so. The only reason they drag on is because the deadline is used as a negotiation tactic - a negotiation that could be done in a matter of days might drag on 2 months because both sides are waiting for the other to blink first and one or the other knows that the longer it goes the stronger their position gets or weaker the other's gets. No manager realises on the 30th August that he needs a new striker after all.
You mention clubs won't be happy if other sides are sniffing around their players during the season, as if that doesn't happen already? Clubs don't start work on transfers the second the transfer window opens - they'll be talking to agents, players and clubs all year round. I'm pretty sure Lukaku is quoted as saying he'd been talking to potential new clubs for months.
As you say, the end of August will just become the week before the new season starts - nothing from this perspective will change therefore it's not a negative.
Again, the only possible negative that can come about by this change is teams inability to react to a sale after deadline day but as I've said, they control whether that happens and it may actually prove to be a positive if it deters players from trying to force a sale.
edit: and the point I was making regarding the injury comment was that clubs build squads knowing that players will get serious injuries. One injury shouldn't leave a club desperately needing to sign a replacement. Obviously you could get an extreme scenario where a club like Swansea could lose Sigurdsson (probably as important a player to his club as any in the League) to a season ending injury on the opening day but the reality is that Swansea couldn't afford to sign a replacement for him anyway.