I don't think other sides needed to strengthen massively to compete with us though to be honest, the gap really isn't too big. Disagree with you on Liverpool, Everton mostly signed a bunch of average/decent players and then finished in an average position, I was never worried about their transfer dealings because the players they were bringing in were mid-table quality. Same with this year, the likes of Walcott, Sandro, Klaassen, Keane, Rooney etc ... they were ok players but never going to worry anybody. Gylfi was the only one that I thought would do particularly well but even then he's nowhere near top quality.
Liverpool brought in Roma's starting keeper (one of the best in Serie A), Fabinho who has been pretty important to a strong Monaco team for a few seasons now and Keita who has been excellent for Leipzig for a couple of seasons now. The likes of Shaqiri aren't worth worrying about, but I think those 3 are players who can clearly come in and should be improvements over their options. Nobody is 'wetting themselves' but I think it's fair to look at them and say that this is a side who have identified their weaknesses and have gone 'feck it, let's back our manager' and gone out and fixed them. I admire the attitude.
You're right that we should probably rethink it after the window closes, just feels like a wasted opportunity to really start the season with a buzz. We're down to the barebones at the moment and it's understandable that fans are uneasy considering the promises/statements made at the start of the window.