Should chess variants that must always end in a decisive result (for a given game played of them) be regarded with at the least some dislike by purists?
This would depend on why this happens. If it is because the game is decided for one player from very early on, then maybe. But if it is because the game's rules steer it away from, or declare a winner for, drawish situations, then maybe not. Thanks to captured pieces reentering the game, Shogi is less drawish than games with regular piece attrition like Chess, but it can still become drawish if each player gets his King to the other side of the board. The official rules deal with this by declaring a winner based on points. Shogi with Impassable Kings simply prevents this from happening. If stalemating your opponent is also considered a win, then the game is very decisive, and I think in a good way.
This would depend on why this happens. If it is because the game is decided for one player from very early on, then maybe. But if it is because the game's rules steer it away from, or declare a winner for, drawish situations, then maybe not. Thanks to captured pieces reentering the game, Shogi is less drawish than games with regular piece attrition like Chess, but it can still become drawish if each player gets his King to the other side of the board. The official rules deal with this by declaring a winner based on points. Shogi with Impassable Kings simply prevents this from happening. If stalemating your opponent is also considered a win, then the game is very decisive, and I think in a good way.