The dev team has added new options for adventurers in the past. The equipment for example is an entirely new feature.
1% of an estate would hardly give them the same benefits as a noble.
1% of a region income is 7 gold a week in most cases. And if additional taxes are in play that can be cut down as much as seems reasonable. 7 gold a week hardly gives you the same resources as a noble. This by no means will mean you can start fielding a unit and fighting in battles. At the very least I don't think it's unreasonable to have the option to buy a cottage and be able to sleep for free in a given region.
Yeomen were a key part of Medieval society and their presence had a huge impact on how the nobility did business. This alteration wouldn't just give adventurers more to do, it would give nobles more to do. Suppose you're 30 gold short on your unit's upkeep, instead of having to beg your lord for more gold you can lease 1% of your land to an adventurer.
Of course this creates new role-play opportunities. The local knights might get a bit annoyed when they learn there's a commoner on their land earning as much gold as they do through several savy business actions. They could go out of their way to attack this man, or maybe even ask the judge to seize his lands. This would give realm judges more to do (I've always thought that position would suffer from too small a case load).
