When role-playing grew out of fantasy war gaming, many of the players were used to playing games with armies of toy soldiers. The first Gygax rules, Chainmail, were intended for just such games, and allowed for the fantasy element...
Dr. Holmes clearly articulates the rpgs have their origins in miniatures wargames, or at least their rules do.
The metal miniatures are not a necessary ingredient of the fantasy game, which runs perfectly well without them.
He also posits that they are not necessary for play of the modern -- in 1981 -- roleplaying game. This comment fits within the context of the book as an example of where Dr. Holmes is attempting to remove any intimidation a reader might have regarding RPGs if miniatures are required. Given that all the pictures of Dr. Holmes playing -- in the book -- include the extensive use of miniatures, I think this is the case.
The fantasy gamer is usually concerned with a few figures representing the player characters and their opponents, and for these encounters the 25mm scale is ideal. There are an almost unlimited supply of figure possibilities.
To use figures or not to use figures, that is the question for the fantasy role-player. Minifigs's Steve Carpenter says that if your eyes don't light up when you first see the tiny armies on the table top, you will never get the bug or understand someone who has.
These quotes exhibit that while Dr. Holmes has an appreciation for the use of miniatures in the game, he is ecumenical about who plays the game. Some people don't understand the appeal of miniatures in the game, that is perfectly understandable. But for those who are merely intimidated by the prospect, he has the following advice:
Another way to get started is to begin playing one of the role-playing games without figures. After the game has been going for a while and has gained a regular group of players (a few will always drop out or join up after the initial games), introduce the first use of figures. There should be figures of the regular characters in the game and one or two monsters. Other monsters can then be represented by small chesspieces, or unpainted figures, or even blobs of plasticene clay.
These sentences add to my earlier assertion that Dr. Holmes' comments that "miniatures are unnecessary" were partly to assuage any fear of financial bankruptcy that may be caused by joining the hobby. Here he adds an economical way to incorporate minis.
He finishes the chapter with this:
There are advantages to having figures on the table to represent the characters in a game...
The placing of figures facilitates [a] kind of dialogue with the referee and vastly increases the ease of visualization. Since many game melees are just that, a melee of characters and monsters running about and in and out, the poor referee finds it a lot easier to keep track of them all when they are represented by tiny metal sculptures. And, finally, the whole thing makes an exciting and pleasing spectacle!
Miniatures use isn't a new part of the hobby. Nor is there a greater financial focus on miniatures than in the past. TSR created their own miniatures company in the 80s under Gygax/Blumes, and lobbied to put others out of business to reduce their competition. They hired Duke Siefried to assist them in the financial endeavor. Miniatures and D&D as an industry have always gone hand in hand, even though D&D in home games hasn't been ubiquitous.