Yeah, the only good solution is to be able to build your own roads. You don't necesarily need an engineer unit. We could let the pioneers be able to build roads as well. This would add to the strategy of their use.
To prevent road spam there of course has to be an upkeep cost. This could also be combined with a one time cost every time a pioneer builds a road on a tile.
It's not tedious to build your own roads. This is a strategy game, and road building can add alot of hard choices for the player.
1. (If the pioneer is the unit that builds roads) Do you build that city first, or start to build the road to the city spot first? Perhaps you ar better of getting acces to some ressources first via an outpost? Hmmmm......
2. Do I build the road arround a spooky monster lair, or do I prioritize to take this monster lair out first, to be able to build a straighter road? (we should also be able to raize roads and rebuild the road network more efficiently later on).
3. You have to plan ahead regarding what threats the road builders can come out for. Do you prioritize troops for this task, or will you rather take the gamble?
4. What is the best route to take when you plan the road that shall Connect city A and B. Just the straightes line, or another route that will make the total amount of road tiles as small as possible later when city C and B is also built?