The problem with your suggested solution is that it increases the impact of good luck for everyone. The result is that everyone's potential score will be that much higher, so the winner will end up being the person who doesn't get screwed out of routes by other players.
As you say, getting lucky with grouped routes does have an impact on the game, and no amount of cleverly playing around your mixed hand will beat someone who gets a cluster of many tickets in an area.
If you're not doing so already, I would suggest trying Ticket to Ride: Europe. While the luck of the ticket draw is still a factor, it's lessened in a few ways:
- Your starting tickets are picked from at least 2 of 4 tickets, where 1 of those tickets is a long route that's only available in the starting hand.
- Stations are available, so if you do get screwed on a route you can still complete it using other people's routes and build your other tickets.
- Similar to the above point, if you're drawing new routes and nothing matches your game plan, you can pick a route that's mostly completed by your opponents and spend your stations to attach their routes to your network, saving your trains.
If you absolutely want to house rule any of the games, you could do some form of ticket drafting in which, as a group at the start of the game, you build a starting hand publicl. For example everyone gets 4 cards, picks one face up and passes the hand until they have 3 or 4 cards. Then you pick out of those routes normally. If you want to go full-out on this you could then draft the rest of the deck and build individual decks, allowing the players to balance how well the routes go together and giving a vague idea of what routes each player might be capable of without having perfect knowledge of what they're doing. You could just do the deck draft and then have each player draw their initial routes from their drafted deck.