Except those two "problems" with rituals really aren't, at least in my book. The reason rituals are designed that way is so that they don't become the automatic solution to every problem. If ritual casting becomes fast and cheap, you're right back to the same problem of spellcasting overshadowing skill use/non-spellcasting classes.
I'll disagree on this one, I definitely think rituals are too expensive and take too long to cast.
I'll start with the time length as I think that's an easier argument. 10 minutes is too long for most of the rituals imo. It makes it so that every ritual is a big deal, and for many of the rituals that's not the case.
For example comprehend language. I think the flavor of a wizard closing his eyes quietly for about 1 minute, swallowing some magical components, and then being able to understand a language is neat. Requiring him to take 10 minutes to do a big ritual every time seems out of place to me.
I personally think the default casting time should be 1 minute. That prevents it from being cast in combat, but does allow a group to use it if they are given a little prenotice. And it maintains the "I am having to use some greater magic" flavor without the "Guys everyone sit down, this one is going to be a doozy" flavor that seems embedded in every ritual.
I don't have a problem with long casting times for big rituals. If raise dead had taken a week, I wouldn't have batted an eye. But the more "mundane" rituals don't need to be that long.
Second argument is cost. Perhaps I'm still old school; I am still getting used to 4e's abundance of gold and treasure per level compared to 3e. But still, paying 21,000 gold to observe a creature for 4 rounds (observe creature ritual) seems extremely expensive. Or that tenser's floating disk takes a full 1/5 of my starting wealth to use when I'm 1st level.
I understand the concern that people don't want rituals to replace everything. But on the other hand, unlike spells everyone can acquire rituals if they want to. Second, even the strongest 4e rituals are not in the same power game as 3e magic. And most important, 4e has been designed so that spells and rituals are never necessary to do the job. Invisibility and Fly have been toned down greatly from 3e levels. Walls of Force no longer block access (though a case can be made that the magic circle ritual can do the same thing). Creatures are not immune to weapon damage and the like, and there are no buff feats that need dispel magic.
Personally, I would rather see a healing surge system be used to supplement the cost. Healing surges are renewable, but on any given adventuring day an important resources (especially to wizards). It also gives an advantage to nonspellcasters, as they tend to have more surges (so less arcana skill but can do rituals more frequently).
Or, allow more free castings of rituals per day. In my game I gave the wizard the ability to 1/day cast any arcane based ritual that was 5 or more levels lower than his level. That was worked great in my game, and has not caused any balance concerns.