i love to solo but the objective is to jump in a party thats your lvl and work together. how it is with most mmo-rpgs. i have solo'd numerous toons of different classes and it never is easy but you learn the extent of your toon
There are also times on shaiya where you get to a point where soloing can be almost impossible for your level, yet possible for a party.
Like a Ranger(HM) goes into the dungeon at canta and gets to a specific room where even going near one mob, attracts them all. Possible with a duo with a priest, but unless you got AP items, or buffs from endgame players, or a party, then you get wiped fairly soon. And if that is the only mobs that gives good exp, then you are forced to level on lower mobs or ones that give less exp until you over-come that set of mobs and level higher.
Of course, if you got the gear and skill to stay alive even after all that, then +1 to you.
One thing to note, even though you don't get the perfect party bonus, when soloing, you do actually get around the same as a party would get(without the pp bonus) if a little less at most.
And sure, it would be great to get almost as much as a PP gets from their pp bonus when soloing. Sometimes party's are hard to get into anyway. But I also see that the game is meant for partying, due to the amount who grind in each area. So partying with the bonus, promotes the idea of partying. If you got a bonus for soloing, then more people would do so, and then less mobs for everyone and more BS tickets about "KS'ing".