It appears that there is indeed an association between pharmacokinetics and development of addiction to psychostimulant drugs.
First, as a general note, it should be noted that pharmacokinetics govern a drug's plasma level, while pharmacodynamics govern the body's response to the drug (i.e. to the drug's plasma level), and in this case, addiction may be thought of as a pharmacodynamic concept, since it is the result of activation and modulation of certain receptors in the central nervous system (more specifically, in the mesolimbic system). These two concepts - pharmacokinetics and pharmacodynamics, or PK-PD for short - when combined together, give the full picture of the relationship between the body and the drug as effect over time, from first contact to biological response.
Another general note is that PK-PD relationship is not always simple to evaluate and explain and is not always 'linear', in the sense that the body's response does not always directly reflect the plasma level of the drug, and vice versa. Therefore, we must not simplify the discussion by saying that the steeper the slope (i.e. the faster the absorption of the drug), the more addictive the drug is, or in other words, the rate of absorption is not the only, and may not even be the primary, factor in determining addictiveness of a drug. Addiction is a multi-factorial condition, based on genetic predisposition, social factors, etc. as well as pharmacokinetics (source).
Now, to be more particular, the slope of the curve in the absorption phase is dependent on the route of administration (and the formulation) of the drug, since different routes of administration provide different rates of absorption depending on the path the drug has to take to reach the general circulation, where we measure its plasma levels.
Thus, common non-oral routes of administration such as IV infusion, intranasal administration (snorting) and smoking all allow the drug to reach the general circulation quickly through small blood vessels in the nose and lungs, or directly, as in the case of an IV infusion. Once a drug reaches the general circulation it quickly reaches the brain (provided its molecules are able to penetrate the blood-brain barrier), and it has indeed been found that rapid routes of delivery increase the risk for developing an addiction. To quote from a very comprehensive review, which deals with that subject precisely:
Addiction is more likely and more severe in individuals who
take drugs via rapid routes of drug delivery. For instance,
addiction to cocaine, amphetamine, methamphetamine, nicotine
or heroin is more probable in people who consume these drugs
via smoking or i.v. injection than in individuals who use slower
routes of drug administration (e.g., the intranasal or transdermal
routes; Barrio et al., 2001, Budney et al., 1993, Carpenter et al.,
1998, Ferri and Gossop, 1999, Gossop et al., 1992, Gossop et
al., 1994, Hatsukami and Fischman, 1996, Hughes, 1989,
Rawson et al., 2007, Van Dyke and Byck, 1982, Volkow and
Swanson, 2003 and Winger et al., 1992). Compared to
intranasal drug users, individuals who smoke or inject drugs
i.v. also use drugs more frequently, for a longer time, spend
more money on drugs, report a greater loss of control over drug
taking and are more likely to overdose (Barrio et al., 2001,
Carpenter et al., 1998, Ferri and Gossop, 1999, Gossop et al.,
1992, Gossop et al., 1994, Hatsukami and Fischman, 1996,
Hughes, 1989, Rawson et al., 2007, Van Dyke and Byck, 1982,
Volkow and Swanson, 2003 and Winger et al., 1992).
That review and the sources cited in it (especially those mentioned in the cited paragraph above) will probably provide enough evidence for this association.
